3/4" lists for about $4.95 where I am. But I go to a park district rink and I think maybe they try to keep their prices lower to encourage business. And there hasn't been any in stock for about a month (we don't get that many requests for it). Bet when it comes in, though, it will run closer to $6 or $6.50. Everything else seems to be going up, so why wouldn't Sk8tape go up, too?
So I think for 3/4" yes, $8.50 is a little excessive. Could you maybe order it from somewhere else next time you needed it? Many people seem to be happy with Rainbo for a lot of their skating stuff.