Uhh... the trailer ad (and seller) both say it should be flatbedded... and that it's a project... holes in the floor, "frame gone"... what else did you have in mind?
If you had a redo in mind (and I can't picture anything else but), then I would go ahead and truck it home... I'd also talk to the seller... I do remember he played his cards close to his vest, and didn't really talk too much about the trailer... so it's a bit read between the lines in my opinion. All indications that it would be a total gut job with frame repair. Additional clues is that the rear corner is held up by the jack in the pics... and that the rear "dent" goes away when the jack is removed... frames shouldn't move that much by themselves.
I can't imagine that trucking that across the country (well, even towing it) would be that cheap...
Adding that to the repair bill just makes the cost higher.
Oh, I do like Evergreen RV (evergreenrv.com) in Shoreline, WA. I'd call them to see if they're up to the task of repair... it's about a 2 hr drive away from where the trailer is. You're going to be paying a hourly repair rate (at about $75.00 and up) anywhere you go.
My 2 cents