My favorite putties are Bondo catalyzed body putty (similar product sold under Evercoat brand) and Bondo Spot Glazing putty ( a solvent putty). Both are typically sold in auto parts stores. Other products include 3M Acryl Blue putty (also an auto parts product). The spot glazing putty will cost you less than a tube of hobby brand, be larger, and last longer. I've also found catalyzed putty at my local Lowes hardware store.
I haven't bought a tube of hobby brand putty in years. It pays to shop around to other types of stores for hobby materials. The model logo adds an additional couple of bucks to the cost.
Check the Tools & Techniques forums for more complete info on putty options