I like Craig's approach.
Here is one I bought - from Sears I think, as they were recommended. It wasn't up to the task, at least with race springs. I'd start squeezing, and something would bend. I'd weld on some reinforcing plates, and try again. Something else would bend. I mount it in a vice, and have gotten so that I can get things on first try most of the time.
The handle was way too short for the force needed, so that got lengthened as well as reinforced (it was flexing).
Not sure Harbor Freight quality ones would do any better. Sure would be nice, though.
Ugly welding, but it did the trick.