Since I got off track & suggested diesel earlier I will try to justify my suggestion here & give some tips for finding affordable & suitable models. First off lets take the fact that diesel fuel costs more per gallon than gasoline. It does & you can use that to your bennefit. Most people who buy an RV use it a few times a year to take their suburban two-income families, 1.5 kids & a dog on vacation & worried about paying an extra 20 cents a gallon for their 1 week of paid vacation when they will use their RV. Take advantage that more americans are ignorant to the benefits of a diesel over a gasser. Sure diesels cost more brand new & hold their value better. People overpay for junk from the start usually buying something brand new from a dealer. These same buyers assume that they can pass along their overpriced goods online so they can buy something all shiny & new. If you are educated to what you are buying than you can end that cycle. Rv's are like cars but more so like boats, bikes,skis,kayaks or other seasonal recreational items that americans intend on using all the time & actually use once or twice. For cars they have there Bible (Kelley Blue Book) & carfax to attempt to determine the resale value of something & then try to pawn it off on others. With RV' they usually have to rely on actual supply & demand of whats listed on craigslist in simmilar condition. With most RV buyers they care more about how the interior/exterior looks than how it is mechanically, fuel economy & dependability wise.
I have been hardcore at buying,selling & trading goods since I was 14 (20 years). I started using Wantads(weekly classified puplications) that evolved into craigslist (5-6 hours a day) as soon as it came online. EBAY is for sellers, craigslist is for buyers!!! The local transaction has more personal interaction where you can negotiate,haggle,barter, & make real time cash in hand offers to real people. If you know what it is your looking for than your online search will be a lot easier. From what I noticed from *happyearthhomes search is that it was probably based on price & location. Actual value & listed price are two different #'s. Everyone inflates their listed price to hedge against potential haggleing in the future. The problem is that if someone initially overpayed due to their inexperience & then does this , they actually start believing that they are asking a fair price. They usually figure out the reality after multiple postings & months of limited interest & no offers or just unlist it & have it rot away in the back yard until eventually having it scrapped. Most people are annoyed by spam & are afraid to put there phone # in a post to avoid weirdos & tire kickers. If anyone who is serious about ruber tramping & wants a long distance machine to live & travel with; educate yourself & refine your search criteria to 1 or 2 keywords on cl. When traveling on the road & or buying RVs usually bigger is better but not always. If you want more bang for your buck & space to bring stuff/others along than this is true. Dont get lost in your search based on the sheer volume of overpriced gasoline powered junk on the market. I know that I have suggested converted school busses for well over 10 years here & elsewhere but will mention it again. There are some budget conversions under cdl, titled as a motorhome & partially converted for weekend Rvs for tailgating or budget camping. Again searching is the key & with limited investment be driving x country asap. For More traditional motorhomes(I.E not slideone/camping trailers that are able to drive under their own power) I have a small list of models that came in diesel & are affoordable.
Winnebago Lesharo/Winnebago Itasca Phasar(sometimes mispelled phaser that will affect your keyword search so keep in mind (1979-1990's eventually changed to a mini Winnie model name Rialta that came with a small gas engine from a chryselr mini van or VW gasser.)
Toyota based motorhomes( these were offered in gas/diesel by Toyota, Winnebago, Chinook, Dolphin,Huntsman & National from 1981-present in US/CA some are even 4X4 & a rare exception to an affordable gas RV that i would recomend) There seems to be a cult following that almost doubles there actual list price. I would value the two above between $3k-$3.5 private party. Keyword i would search for on cl (lesharo, or renault diesel, winebago diesel or winebago toyota, or just toyota in RV section. example
http://baltimore.craigslist.org/rvs/2709341061.html
These are just 2 small affordable Class C motorhomes that are fuel effiecient thatI would recomend that can be parked on the street of a major city (aka a curbside Rv & both models came in diesel if you look). They are bigger than a VW vanagon/eurovan, Class B or US chasis based conversion van (they usually have a bed ,tv,vcr,dvd player but lacking a generator,bathroom & cooking features. Not as complete as a Class B,C or school bus conversion or Class A motorhome. If you have between $5k-$7k you can find some great big Class a's or completely converted full size school busses that have generators, bathroom, cooking/tvs. Jump on them as soon as they come available. Keywords in RV section for a bus: bus diesel, converted bus, conversion, converted, titled. example
http://kenai.craigslist.org/rvs/2638291890.html
If converting a school bus from scratch is a project you want to tackle, there are plenty of cheap buses around but what are the unforssen costs & issues that will inevitably arise. Keep in mind all that it will take to get it road ready, re titleing can be a big issue including painting since illegal in some states to be painted (National school bus chrome/ or in lamens terms: yellow). Removal of seats, govener, adding tanks for water,waste, & lets not even get into waste veg oil if that is the direction you are going in(its NOT CHEAP). You will most likely need to do regular mechanical repairs & potentially change tires to something with a higher speed rating to recieve an inspection sticker. This is all before you start building built in storage,furniture,walls, wiring & furnishing with mattreses/futons or other sleeping arrangements. Its much easier & cheaper to buy something where the previous owner did most of the big work but never fully converted & remodel to your taste. They will most likel havey lost interest,storage or both & or an out of money. Take advantage of these known facts & save some time, money & agrivation by taking whatever RV offthere hands. As teh buyer you are doing them the favor not the other way around. The market for used RVs is limited to frugal types like us & or the uneducated tailgater,camper consumers that will pay out the nose for junk.