DD, my advise would be go to an RV show and look at everything to get ideas as to layout and prices. Actually being in them and feeling the space or lack of it will give you a better idea what will suit your needs.
Like Jim said check for delamination. My neighbor has a Terry trailer and he has problems with the fiberglass delaminating. You can see bulges looking along the side. He bought his the same year as us 2008.
Ours is a Grey Wolf (by Cherokee) It is just a base model around 20k for the 28BH model. We are happy with it but we have it parked at a conservation area on Lake Erie. If you are travelling I would definitely equip it with an equalizing hitch.
Although some people do have problems with slides, I would never buy a trailer without one. That extra 18-24" makes an amazing world of difference to the living space and the feeling you get inside it on a rainy day or when company comes calling.
If your plan is to live and travel in it, take Jims advise and get one that is well insulated. On most cheap trailers (like mine) the insulation is of little to no good. When I go to check my trailer in the winter I swear its colder inside it than it is on the long walk from the road into the park!
I would advise any couple buying a trailer or boat to buy the model that suits their own needs. The double/bunk at the back of our trailer that we thought would be nice for company is rarely needed(except to store crap on) and my wife and I would far rather have a bathroom with some room in it!
The roof is one area that ages quickly on the cheaper trailers. Mine is parked under trees which is hard on them but so is being parked in the sun all year.
If I could redo I would also look at one that has the 2 lazyboy chairs instead of the futon that mine has. It is not the most comfortable thing to sit on or sleep on. :disgust
Regards, Rob