Yep, look up astronomical suppliers. There used to be a place called "" (give or take a hyphen) that would sell all the grits you could want from 60 carborundum down to rouge. For grinding a lens, you're going to want 60 to 90 for roughing, then 120, 220, 320, 600 (silicon carbide to this point), 15 micron, 10 micron, and 5 micron (aluminum oxide for the fine stuff). Some folks use 3 micron alox as well.

Once you're done removing glass, you'll need to polish; that calls for optical pitch (though I've heard of one fellow successfully using road tar and another tempering roofing tar to get usable pitch) and some kind of rouge. The most common now is cerium oxide, but some folks use tin oxide and a few prefer to finish with genuine rouge, an iron oxide compound (but watch out for lumps in the red rouge, they'll scratch your glass).

I'd also very strongly recommend working with a local telescope making group to gain the hands-on experience you'll need to make a lens. A simple lens (one element, plano-convex, like the objectives Galileo used 400 years ago) isn't difficult to make, but if you want to make an achromat or more complicate lens you'll be looking at developing some considerable skill before you get one that's usable.