Isn't that like $15 at Pelican? It's not hard to replace just be sure you have the right o-ring and that it seats properly. Bleeding the system can be difficult as well. I haven't done this myself, but I'm thinking that it'd be a lot easier to pull the manifold like they're saying. You'd need an upper gasket for that. No need to pull the throttle body (those gaskets are metal and often re-usable), just disconnect the throttle cable & have at it.
I suppose I should ask "What kind of jobs have you done on cars?" before I advise you to try this. If you do it wrong & the motor overheats, it'll crack the head & you'll really be out some money.
This isn't a difficult job. It's just hard to get at the pipe, maybe the shop is adding the usual surcharge for old cars that fall apart when you try to fix them. Most posts I've seen here are related to the famous
"hose delete mod." That pipe cracks all the time. You might want try that all at once...it's not too difficult if you have a pretty good selection of tools.
BMW OEM
from Pelican is $19 + shipping. The generic is only $11. I'd go with the OEM, some have reported that the generic doesn't fit. The
necessary o-ring is $1.50. I'd also consider some water wetter ($10), I have it running in my car and it seems to help. Beware that the water wetter may make the temp gauge read a little higher. Mine sits reliably between the half and 3/4 marks all the time.