You don't say quantities, but I sure would not want to crank a manual surface grinder for what is basic production flat grinding. Get one with a micropole chuck that you can fill up with the order, nest/block them all snug, dress the wheel, set the stops, turn on the coolant, push the go button and do something else while it runs.
There's a lot of smallish surface grinders with 2 axis autofeed out there that aren't priced much if any more than a manual fed machine. The only reason for a manual machine with hard stops is if you do a lot of finicky tool making/grinding.
You want a fine pole chuck if the work is thin and small. For absolute size control without (significant) warm up time, a permanent mag chuck is better. For strongest holding along with a range of reduced power options, an electric may be better depending on your work.
6-18 grinders are about the most common. Sometimes a 6-12 may be a little better priced due to the "short" table. But the most cost effective options are going to be in that range. I know plenty of auto 6-18 machines in great shape sold for $~800 or less in the past few years. Just helped a buddy move a very nice auto DoALL out of a recently closed toolroom in Yonkers right before the holidays. It cost less than $200, about what the diamond wheel on it cost, for the whole shebang. It was on eBay, nice original paint, clean, with good magnet and set up for coolant. Maybe no one else wanted to move it in that neighborhood?
smt