Originally Posted by operator

Ballpark ~ $100 total for headset + fork. If you're not deadset on going this route, you can stick with the threaded fork (unless your bike didn't come with one) and grab a new headset. We gots Tange $10-$20 or more expensive shimano cartridges up to 105 level in stock.

If you have the original fork you may or may not have enough threading on the fork to accomadate the newer cartridge headsets. Bring in frame/fork unless you can write up all the measurements.