What I've done in the past to meet a spending threshold is purchase GCs from the supermarket Gelsons. They also sell GCs for many other retailers: Home Depot, Crate & Barrel, Barnes and Noble, Nordstroms, ITunes, Bed Bath and Beyond, Starbucks, CPK's etc, etc. So with my one Gelsons' GC I can use it for groceries there, but also can use it to purchase other GCs - so I know without doubt I'll be able to use up the balance.

Many supermarkets and drugstore chains sell other retailers GCs. You'd just want to doublecheck with the store b4 purchasing its GC that you'll be allowed to use their GC to purchase other retailers' GCs. Gelsons is the one I have experience with.