Staples has the 32" x 40" foamcore in black or white. 3 packs are $22.98 or something reasonable. One of the few truths in photography: You can never have too much foamcore and it can never be too big.
Love & Bass
Hobby Lobby the craft store or Hobby Lobby the hobby store? This would be good as with the other hobby, RC, that paper can be a real pain in the you-know-what to peel off when you actually want to peel it off.If you are wanting foam core to last, do not get it from hobby lobby. I used a lot of foam core in school and the hobby lobby foam core had cheaper foam and adhesive. It was a pain to cut and usually pealed apart. If you are going to get foam core I would suggest an art supplier.
That's funny because for several years I've looked at the hobby store website, talked and read about it on the RC forums, and someone mentioned the craft store one day. I always thought there was only one type also, the hobby storeto be honest I only thought there was only one type of Hobby Lobbybut I guess I am talking about the craft store.