Welcome to HTW...!!  What have you got for a "tow vehicle"? No point in looking at a trailer that your truck can't pull. A half ton truck is not going to handle a 10' LQ, three horse steel trailer, etc.....

There are numerous levels of quality in both the way that Trailers are built and how the LQ is built.  These all affect the price that you will pay. Of course a private party in hurry to get ride of a trailer will be cheaper than a dealer trying to cover his over head.

Most trailers that have anykind of a LQ finished in the trailer will usually be at least 7' wide. Some 7'3", 7'6" and 8' wide being the largest.   the narrower trailers are easier to see behind. Your truck mirrors work well with them, 8' wide trailers need the truck mirrors extended out to see around the trailer. The wider the trailer the easier it is to catch and break the truck back windows or damage the trailer if you jack knife to sharply.

Trailer height is another option.  Mfg use less metal to build a 7' trailer vs a 7'6 or 8' tall trailer.  Won't matter much to most horses. But makes a huge difference to you when you sleep in the Gooseneck area and want to sit up with out hitting your head.

The other options that you will be offered in trailer designed for camping is mangers for the horses and under manger storage.  This is great storage and I don't think you can get enough storage space.  On the narrower trailers, your mangers need to be narrower than on a 8' wide trailer.  Managers do add weight to the trailer, They do reduce some of the options inside the trailer.  With out managers I can fold divider panels against the front wall and make larger stalls. I've done this to crowd 3 horses into two stalls when I've needed to haul an extra horse. This is not practical with the managers

LQ come in a variety of choices.  Slide outs over a LOT more space, But add weight and complexity to trailers.  Good and cheap, probably doesn't include slide outs.  Custom builders put in sold wood cabinets and lots of neat amenities.  Production interiors mostly use prebuilt or Partical baord cabinets that have a wood veneer or vinyl veneer that replicates wood.  Good and cheap means that you are probably looking at the production based interiors.

Good luck.

I appreciate the help, however, do you have thoughts on brands of trailers that are good and ones to be weary of?  Slides are not important to me for a horse trailer, they are very nice, but for what we plan to do, being inside will be for sleeping and storage.  A fridge/cooktop/ and microwave is nice, and I would prefer those, a cowboy shower is sufficient and the other things can be dealt with.  My concern is finding a good trailer, with a good floor that I have peace of mind when I am going down the road and not having to worry about the safety of the horses.

There are many trailers that are available, and finding a good and cheap one will be difficult, but finding a good one that is affordable is much more possible.  Do you have any recommendations of what to look for when viewing used trailers, what should I be cautious of? 

Thanks again.

There are numerous regional manufactures you may want to consider. What part of the country are you in?

Good Luck in your search!