The characters in the guild store aren't likely to be moved or added anywhere else. The only times I can remember characters being moved (but not removed) on a table were when CG wanted the Ebon Hawk (I think) and relic materials on the later cantina nodes, but there were already characters there, so they were moved to the easier stages. I don't recall store characters ever being moved out of a store.
So you'll just have to save guild currency and check the store every refresh.