When we decided to start camping in a travel trailer versus a tent, I started with a cheap used model to see if we like it and how expensive it was with towing and all.
I found a 94 Skyline Nomad 2610 (29ft overall) for only $4000 with little use and a one piece galvanized roof installed from the factory. Queen bed up front, couch and table fold to full sized beds plus two full size bunks in the rear and full bath with tub. It weighs about 5k empty and my 03 RAM QC 4x4 HEMI has no problem hauling it anywhere we go which is usually straight through the White Mountains with 4 in the cab, load of wood in the bed along with 4 bicycles, grill, etc... Due to drag, it actually feels heavier towing than my 6x10 dump trailer loaded to 8k lbs.

Now that we know we love camping, we are currently shopping for a newer unit with a slide as we typically have family and friends come along. With 5 adults in the trailer, it gets tight.
I've found many friends who say brand new is not worth it. One example bought brand new for $26k. 5 years later they owe $19k and it's only worth $13k...
Personally, I feel 5th wheel campers seem smaller than equivalent length travel trailers but are easier to tow and back into sites. I say stick to 30 feet (33ft overall) max. It's hilarious getting setup then watching the guy with the 36-40 ft camper spending all afternoon trying to squeeze into a back-in site.
Lastly, if shopping used check the fridge. They can cost upwards of $1200 to replace or around $500 to rebuild. Pretty sure mine is leaking a little ammonia...