I think Maintenance is about $100 around here. I've brought my Pfaffs to the dealer I bought them from. I only have one but have traded up to newer models a few times. I have the latest one about 3 years and haven't had it in for a check up. I should as it's still under its 5 year warranty so there is no charge.
Only problems I have are minor, the warning that the bobbin is almost empty doesn't come on and the automatic threader is off. I make them adjust the auto threader but rarely use it as it always goes out of wack. I'm lucky that I can thread the needle OK. If you're having a problem seeing the hole in the needle try using a metallic needle, the hole is larger.