This is such a sad situation. The end goal here is to get your money. Perhaps you can approach her honestly and ask what happened in her mind from the original discussion about price and now. (Certainly not much time has gone by for her to have forgotten it.) Tell her that you are crushed and must assume that she is disappointed with the result. Her attitude during this discussion will reveal a lot, especially if you remain calm. If you look like you are about to cry, that might even help (and it wouldn't take any acting for me if I were in your shoes). If the discussion reveals that she is short on cash, then give her some options: a payment plan might be in order or offer to contact some of the other relatives to get the money. Tell her that as a last resort, you will consider displaying it for sale in public. Who would want their family's heirloom displayed where the whole community can see it?
Best wishes on this one -- the quilt is beautiful!
Dayle