The back catch is pretty minor but dependent on your model, they may not have the parts anymore. Lense cleaning at Canon is around $80-$120. To replace the shutter block, you are looking at around $150 upwards, (had to replace mine for the EOS 500, 50 and 5 due to the infamous leaking lubricant problem.)
when my wife's pentax broke down, the service centre quoted me $170+ to repair. in the end, we both decided its not worth it.
actually wanted to get ur lens, benedium. but, i remember reading here b4 dat once u send the lens for cleaning, some of the lens coating will be gone too - ie colour reproduction, contrast etc... may be a bit off. since i going to use it on film.... oh well. :cry: