Jared..it depends on how big a hurry you're in. One seed will eventually make a perfectly good clump of any of those grasses. If you want a clump with a larger girth, faster, you can use as many as 12-15 seeds per cell.

The obvious answer to your other question is that you can almost always buy larger quantities of anything for less than smaller quantities. At Jelitto, for example, you can buy Blue Fescue seed for 3 Euros for 1 gram, 24 Euros for 10 grams or 192 Euros for 100 grams.

Here is a link that might be useful: Jelitto

Thank you very much... That number gives me a good idea of how many seeds I would need per flat. I planted festuca glauca seeds in the past but I sowed them all in about 4" containers but I only got a few plants out of that, so I gave up. I think plugs would be much better and cheaper.