Your mother-in-law must be quite proud of you to brag so much to her friends. I'm not sure where the requests for expensive gifts come from though. A gift is something you give from your heart. A gift is thoughtful and meant to be treasured.
I simply can't imagine someone approaching me and expecting me to provide them with an expensive gift. If that were to happen, I think that I would ask them what do they really need?
If they are truly in need, then they would not expect an expensive gift.
Perhaps tell your mother-in-law that you appreciate her kind words, but you are not Santa Claus and every day is not Christmas.