Are there Arduino UNO R3s which use a crystal instead of a ceramic resonator?
(Frankly, I don't understand this cheapness: if you really want to save on component cost you can run both AVRs on the same crystal. The 16U2 always has a crystal.)
Some of the Freeduino boards use crystals although the newer ones now use a cheaper USB to serial chip (the CH340) instead of the Atmel chip used on the Arduino Uno.
The diavolino is another build-it-yourself board that has a crystal. I am sure there are many others. The ruggeduino is another that uses a crystal and also markets itself as being practically indestructible. Their "How to Destroy an Arduino" is well worth a read for things to avoid doing to your Uno.
It appears that the Arduino Leonardo uses a crystal:
On the Sparkfun site it's the same price as the Uno R3, so I think I'll go for the Leonardo.