going to replace bearing in lower bracket,is it difficut,i belive it has bearings not sealed,looks easy if you get crank arm off,this is a mid 80s sprint..bike shop wants 100 dollars..is that too much....any help...

Bike shop is full of it. Should be around $13 to 20 for a cartridge bottom bracket, and labor around the same. $30-$40, so about half that much. That might have been a full tune up PLUS the bottom bracket replacment?,,,,BD