I think you should buy the clearance fabric with household money and save the GC for something just for you or for something lasting you'd not normally buy. When I have a gift card, I try to use for something I can pinpoint and thank the gifter for, not just 'normal' stuff. It was given to you, not the house.
If a batik quilt is what you want for yourself, then wait for the batiks or splurge and buy them full price. At Connecting Threads, they aren't expensive.