Mostly the problem I find is getting a small pocket sized project box, the size of a Altoid/gum tin.
Eclipse gum tins work nicely here in Australia, just a few dollars for the project box, stocked at most supermarkets, petrol stations, newsagents...
Jiffy boxes (the "UB" series plastic boxes) don't tend to go down to a 'comfortable in the pocket' size, but I agree with Dave, they are good value if they fit the purpose.
My next small project is being built into an ancient Seagate 40MB laptop hard drive chassis, that does fit nicely into the pocket though a touch heavy.