I just bought 2 midriff covers from Unicorn belly dance supplies
Belly Dance Supplies, Bellydancing, Costumes for Belly Dancing,and Belly Dance Music
They are made by Danskin, and are a fishnet weave but a small weave. Quite stretchy, and one style is seamless which was what i was after, you need to put hooks on the top though to attach under the edge of the bra. I also have one of the ebay ones from Eralla in Australia, that is OK as well.