I bought an LHT frame and built it up. Here were my reasons at the time:

• The LHT complete was on the horizon but not available yet and I was in a hurry.
• I was worried that they might cut the steering tube on the complete and I wanted the ability to have it high, due to pain in my hands and wrist on my other bike (which I now know was due to something else.) Pretty foolish because I don't think they cut the steering tube on completes of any size, and mine is a 62cm.
• I wanted the experience of building up a bike myself. I have done a lot of wrenching over the years, but this would take my skills to a new level. (I even built my own wheels.)

The positive results were that I got a good touring bike with a blend of compenents that I feel good about. I learned a lot about working on bikes.

The negatives were that I spent MUCH more than I would if I'd bought the complete, I ended up with wheels that aren't exactly round (though they survived their first tour unscathed and my local guy pronounced them "pretty good for a first attempt, and tour-worthy"), and I also had an issue on my tour due to my own error in assembly. I didn't torque the lock ring that holds the cassette on the rear hub tightly enough, and it came loose. Luckily, I had a Hypercracker. I spent an hour or so by the side of a highway in eastern Washington fixing it - unsuccessfully. I still didn't torque the thing enough. It came loose a second time, and this time I torqued it better. It hasn't come loose yet.

My recommendation, if money is a big factor, would be to buy a complete bike. The manufacturers buy their components in huge lots for low prices. You can't compete with that. You don't really want bargain priced, suspect components from Ebay on your new baby, do you? I didn't, so I only have a couple of Ebay items on mine; the rest were bought brand new.

If you want the experience of building it yourself, great, but know what you're getting yourself into. Not only did I spend a lot on the parts, I also spent a lot of money on tools. I didn't mind; to me a good tool is an investment, but it's a factor to be considered. And after all that work and expense, I think there's a good chance you'll have messed something up, which could be inconvenient, as it was in my case, or expensive - like stripped threads on the frame.

I wouldn't try and argue that the LHT is the best touring bike available, though I would argue that there aren't many bikes that are significantly better. I would argue that it's a really good tourer for a really good price. The Trek 520 is a bike I'd consider. How much more expensive is it? I saw a Cannondale tourer at my LBS this week - the one with curved forks (I'm not sure of the different C'dale models.) It looked beautiful, and I've heard really good things about Cannondale tourers, but they wanted $1800 for it.

There are other worthy tourers - Novara Randonee, Fuji Tourer, Windsor Tourist (I think that's the name), the Thorn, the Americano, Rivendell, Bruce Gordon, Jamis has a good one, and I'm sure there are others I can't recall.