I need a recommendation please

I'm looking at getting a spot weld cutter and would like to hear any feedback from those of you that have bought them in the past. I see a bunch of them available on E-bay but not sure which way to go. Size? Brand? Arbor and Cutter type? Drill bit type? Etc.
Thanks, Mark
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Thanks for the info guys......anyone try one of these?
Spot Weld Cutter - eBay (item 220705495270 end time Dec-09-10 14:04:34 PST)

3 pc COBALT SPOT WELD CUTTER WELDER DRILL BIT SET - eBay (item 230459771633 en