A while back I bought a DeWalt grinder (4 1/2" 5/8 spindle) and it was a particularly good deal, because it came with a bunch of grinder- and cutoff wheels. For good measure, I bought several contractor boxes of these wheels. DeWalt makes good tools - This thing has very little vibration, slow start, not too noisy. It is a great tool.
I had over 50 of these cut off wheels so thought I was set for a while.
Boy, was I wrong: I've been going through cut off wheels like a fat kid through cake, so needed to replenish the supply the other day.
To my surprise, 4 1/2 " 5/8 spindle cut off wheels are very hard to find locally (Sears, Lowes and Home Depot - nada). On the other hand, 4 1/2" wheels 7/8 spindle can be found like empty beer cans at a frat house - everyone and their mother has them, seems like. The 5/8 spindle type I did find were over $6 a piece(!) and lasted less than a half hour.
I ended up buying a new cheap ($30) grinder with a 7/8 spindle. The cut off wheels are under $2 at home depot and lowes.
So the moral of this story is, before you buy stuff, to make sure you can find consumables locally and at a decent price.
Remco