Rough cost of fitting/ coding ECU

Hi, has anyone ever had a replacement ECU fitted to their vehicle? I'm due to get one fitted soon on my V reg Golf TDi (AJM) and was wondering what other people have paid in the past as a rough estimate. Any info would be appreciated.

Also, started the car this morning (it usually takes a couple of attempts), and while turning the engine, there was a kind of echo/ hollow sound coming from the engine, at least I think. Could this be caused by a compression leak or something or other? Thanks in advance for any ideas:Blush: