Speakers at our guild often bring supplies from their stores (notions, patterns, pre-cut fabrics, kits with fabric and patterns together) I think it would be rather hard to bring bolts and have to cut fabric at the meeting, so maybe a supply of the pre-cuts and bundles you said you had. Maybe hand out discount coupons for your store so you get new customers. If the guild has door-prizes, perhaps you could donate something for that.