Hello,

It looks like a Mamillaria kelleriana to me.

I wish I could buy specimins that size for just $2.00.

Thanks baldric. Now I know what kind of cactus I have. I should have picked up a few more of the other varieties they had for $2.00. The vendor said he had too many and wanted to get rid of them. I have to overwinter them indoors and my space is limited otherwise I would've picked up the whole lot.