Actually, since the Pro/200 is so expensive now (Intel pushing th
180), the 200/512k is actually only a couple hundred more.  If
you are going to spend the $$$ for a Pro/200, get the 512k chip.
Otherwise, the 180 is much cheaper (slower bus, unfortunatly).

The Pro/166 with 512k cache is also pretty cheap (from Intel, 1000
qty), but I haven't been able to find a reseller with it.
The Kalmuth with have L2 running at half the speed of the CPU,
but you should be able to get much larger L2 caches.

Kevin