I'd guess about 30 minutes for an experienced machinist to do what you wanted. Gone are the days when you turned up on a friday afternoon with a slab of beer and got the job done for nothing
Sounds like they didn't really want the work and quoted you an over the top figure to get rid of you. I can't understand this - if your shop is too busy or you don't want to do it for some reason, then why not just say so?