Or StockingsHQ!
I've got some really pretty fashion opaques from there, although this winter wasn't so good for them.
If you find fishnets more durable but aren't keen on the look, try lace stockings.
The Transpareze Sara stockings are very nice and at 20d they're a more durable sheer stocking.
Or you could see if any of the cheap options work for you. Silky's Super Shine stockings and holdups are good.