Another useful place to look for crystals of different frequencies is on old circuit boards. You may even have (as I do) quite a pile of old ISA boards laying around that have numerous oscillators and crystals soldered onto them.

You may also consider trying to locate a local surplus electronics outlet that sells old junk electronics. The 8051 has been around for so long that it is not at all uncommon to find surplus contraptions that have 11.0592 MHz crystals inside.

Yet another place to look is on some older PC motherboards. Some of these have crystals that could be useful.

Michael Karas