Welcome to Techimo, htexans1!
If you're interested, I have an Asus P5A (ATX) with a K6-2 533 for $25 shipped.
Product link
Those K6-3's are really hard to find these days, and when you do find 'em- they're expensive.
I don't know if you're aware of it, but the P5A/P5A-B series boards will also run the K6-2+ and K6-3+ CPU's. These were originally designed for use in laptop computers, made of a thinner core process, and very much overclockable. A K6-3 450+ will easily reach 600Mhz, which is a tremendous OC for these chips.
In order to run these "+" chips, your board revision must be #1.04 or lower, and you'll need to flash the BIOS.
(Revision number can be found near the PCI slots)