If you ever plan to do a tile job (counter, floor or whatever) these are the spacers I recommend.  They are made by Tavy.  I have only seen them at Lowe's, but they are worth any extra miles you might have to go.  The first spacers I bought were the regular X (or plus sign) type of spacer.  They work ok and they are cheaper but the Tavy spacers are MUCH BETTER!  They don't fall over (or in between cracks) like the others do.