Our guild faced the same dilemma and we did three things:
1. contacted national, regional, and local LQS and organizations/manufacturers by personal letter and/or email to request door prizes. We received enough donations from these contacts to cover 2 prizes each month;
2. scoured the Dollar Tree and other local discount stores for things that could be used by quilters; and,
3. requested each member to bring something in that they had multiples of or did not use that could be donated for door prizes. A member could also make something to donate as a door prize, if they preferred. The latter led to several unique door prizes and several member-led classes and demonstrations for future meetings.
We managed to cover door prizes for almost 3 years in this manner and everyone was satisfied with what they received. Hope this helps.