I doubt you can get the real St. Ives (?) transformers for under $60, but maybe I'm wrong. Vintech actually distributes those transformers now, and they were original Neve issue and a big part of the sound. They distort in the low mids, which gives it part of that "thing" that everyone loves.
The only thing with building them is having the test equipment to make sure they are properly calibrated and are not oscilating at any wacked out frequency, and they wont calibrate themselves, if I understand correctly. They also have to spec from like 5hz to 40khz to pass the test.
I'll let you know. I think Ammeth has the Vintech, ask him about it too.