I'd avoid 57's on toms. They work fine for live toms, but in the studio they can sound like ass. The EV N/D408's are good affordable tom mics, as littledog posted.
I think some of the best tom mics are the Studio Projects B1 and B3. And the good thing about them is they're very good mic for other applications such as acoustic guitar, amps and even some vocals. The B's are also great on drum overheads.
SP B's were used on toms on the two songs available for MP3 download here
http://www.thelisteningsessions.com/jazzooo.htm
N/D408 on rack toms and B3 on floor tom in all the mixes on Sessions 6 & 7 here
http://www.thelisteningsessions.com/sessions.htm
littledog makes a good point about the OH mics also being important for tom sounds, and many great recordings only use OH mics and no direct tom mics.
For great affordable OH mics, check out the Oktava MK319 - they're super cheap at GC right now - I think like $50 or something. Definitely under $99.
It might be good - if you're just starting to record drums - to go with 4 mics total: OH pair, snare and kick.
A great set of mics for that kind of set up:
OH: MK319's or B1's.
Snare: SM57
Kick: ATM25
If you then want to add tom mics, B1's only run $79 each - so you can do it cheaply. And also use the B's for other applications besides toms.
Good luck!
Dan Richards
The Listening Sessions
The Project Studio Handbook