Do you have a link to the type of fabric box you would be making? I think price would depend a lot on how big they are and what they look like.
I've read that the microwave bowls can catch fire, so not all venues want to sell them (liability issues?).
Are these the only two things you could make for the fundraiser? Pinterest shows a lot of additional ideas:
http://www.pinterest.com/janissfletc...draiser-items/
Edit: Also, I have seen where a raffle quilt is often the single biggest-ticket-item for a fund-raiser -- often over $1,000 provided tickets are sold before the event as well as at the event. $1/ticket or 6 tickets for $5 usually works really well. It helps for sellers of tickets to have a good color photo of the quilt to show. Of course, you need to live in a state that allows raffles and abide by whatever state laws govern them.