My husband hasn't been happy about the HF or Red Trailers for our build, since we're designing a TTT, which will be a little larger than a tear, and he wants a little more substance under us.
I have talked to several welding shops, and the price for a custom trailer (which is really just a flatbed, of sorts) is in the $1300-$1500 range - choke, cough...

I happened upon a site yesterday for flatbed trailers from a guy on the outskirts of Portland, Oregon, which isn't far from where I live.
He's got 5x8 (and up) flatbeds on 3500# axles, with 15" tires for under $700. The 5x10 I'm looking at is $675, which isn't much more than we'd be looking at if we did it ourselves and certainly beats the custom welding estimates I've been attempting to choke down over the past few weeks. We don't need the decking, lights or fenders, and I'm working on getting a price-break off the $675 since we don't need that stuff. Not sure if I'll get it or not, but it's worth asking.
If anyone is interested, the guy's website is http://ms-trailer.com/. Of course, you guys may already know all about this guy, and have probably uncovered some great and wonderous secret about his trailers that I'm not yet aware of!

Leslie