If your sister puts it on E-bay have her start the bidding at $300. She can always come down if she gets no takers after a week or so. I think you can advertize on places like Craigs list also. Make sure to mention the handquilting and embroidery.
I quilt at our local Senior center. We raffle off a quilt we have handquilted every year. They usually make at least $1200 or more.
Years ago a made and donated a quilt to our church auction. When the bidding was slow getting started I ran the price up by bidding on it myself.
Your chairity needs to raise it's prices. People don't value things they get for little or nothing. We have one like that in our community. They charge $.25 for paperback books. The same town has a Good Will store that charges $1.66 for a paperback book. The Good Will sells a lot more.