If you have lots of patience, I would recommend trying it yourself. I tackled a TH400 w/o any help, other than manuals and such, and found it a great learning experience. It certainly won't save you any money, but the experience is valuable. If you are in a hurry, or unsure about yourself, farm it out.
About specialized tools, you don't need the tools the manuals call for. The only "specialized" tools I required were some ready-rod and washers to pull the front pump, some feeler guages, and a dial indicator for end-play. Oh, and some 5" c-clamps for the clutch drums. And you will need to grow some new skin on your fingers and knuckles when you are all done.
Email me about it if you want.
Ryan Hoskins
[This message has been edited by Ryan Hoskins (edited 06-29-99).]