any hobby electronics store ?
make sure you take note which value you desolder from which place. Actually you could also track it down through schematics/pictures later, but it will save you lots of headaches.
When buying replacements, the F value should be the same (22pF for 22pF) but you can buy a replacement with higher V tolerance. for example if a cap is 22pF 10V you can put in a 22pF 16V there without worries.
