Dan's Small Parts had collections of parts as I recall. A low cost alternative to "grab bag", for some things, might be to carfully review some projects, chat with others, etc, to see what common or general purpose components might be used. In my hobby (ham radio) a lot of projects use things like 2N2222, 2N3904, LM317, 741, etc (transistors, voltage regulator, op amp and so on) which are low in cost from Jameco and other places. You may also see that some common values of resistors and capacitors pop up. The point is that for some things, you might be better off buying a handful of commonly used parts of known values. Don't get me wrong, there's a use for grab bag stuff at times too.