Unfortunately its all in the eyes of the beholder. Older units are heavier, maybe a better frame, little less plastic. Appliances are just that as they are today, same mfgs. different models, some work better than others. Older units will have less bells and whistles, electronics, remotes for whatever. On the other hand its just so much less to fail.
If you're buying privately, (remember it's 'as is') make sure the unit is plugged in, water system has water in it and is pressurized. Spend a couple of hours and try everything, AC/DC/LPS. Run water into the black tank, gray tank and crawl underneath and check for leaks. Check interior "eveywhere" for stains,and mould. That means every every cupboard, nook/kranny, that includes the storage and basement. Make the DW walk around the interior and do the "smell" test. Very important.
Bring a tire guage and pressure guage. If the air pressues are low chances are good it was run that way. Do the tires show cracking or checking, thats another +$1000 when you bring it home. Crawl underneath and visually inspect the frame for cracks or excessive rust. Since your truck is ready for a 5er, hitch up, test the brakes and lights and make sure it fits on your truck. Don't be surprised to spend another $250 to $500 on brakes.
Bottom line, make a list of what's important to you and spend the time to check it ALL off. Try to find a one owner, weekend camper who stores the unit at home.
Lots of information here on site to make a comprhensive check list.
With your 2003 F250 you're limited just as I am (2000 F250) with an 8800 lb. GVWR, so I'd keep that in mind off the top. 10,000 lb. GROSS weight for your 5er should be an absolute limit. (That'll likely put your truck over its GVWR.) So, while some of the older Hitchhikers and such might be great 5ers, I wouldn't want to tow one with my F250, and the same would be true for other "high grade" RVs.
You'll probably see a lot of Jaycos, and I think most would agree that they're good RVs. We had one for several years and likely it. We had a wheel bearing overheat and ruined the axle on a trip and decided to trade for a new one rather than spend precious days awaiting a fix; otherwise we'd probably still have it. We had several little problems with it, but I don't think I could blame Jayco for any of them.
I should also mention our present 5er, a 2006 255RKS Puma. It's an inexpensive camper, but that means you don't have to get into the really old ones to get one near your price point. Ours has some hail damage and fading, but otherwise is almost like new, and it wouldn't sell for much over your $7K (partly due to the hail damage).
Buying a several-years-used trailer has advantages other than price.
How well the manufacturer will honor the warranty, or even if the manufacturer will stay in business, no longer matters.
Anything with shoddy design or construction will likely have already failed, or broken, or leaked, or been discarded and replaced. With few exceptions (tires) whatever works, seems well maintained and has stood the test of time should be good for years.
But it can take a good long time to find someone who has what you want, has used and treated it well, and wants to part with it.
Thanks for the feedback. Newk, how can I verify my tow weight limit? I was under the impression that my limit was closer to 12,500. Thanks,
Paul : -)#
You are correct. On my 2003 F250 the GCVWR is 20,000 lbs. Where there is a good chance of being over the weight rating is on pin weight or payload capcity. That can be resolved with air bags to level things out. The only difference between a 2003 F250 and 2003 F350 SRW is an extra leaf in the rear spring. The rear axle rating is the same. This of course assumes the same rear tires and same Rear End ratio.