I think the prices you mentioned are fair. I would even mention the difference to her. I have purchased homemade stuff from friends and craft shows (small items like soap) and there is usually an individual price and a quanity price. Making the individual price actually for two is a nice little pair (and reasonable in price). Then a bulk price of $10 for 8 is offering a nice discount for buying more.
Your time, work, and consideration for doing this is certainly worth these prices.
Now I have to ask, Where did you find the netting?