I've been an installer for a few years now but I have only once done any tear out work. I have a job coming up that requires me to first remove about 500 sq ft of the clients original 5/16" thick solid 2 1/4" (if cheap looking) hardwood. I think it's fastened with the little staples from the hand guns that are used for engineered boards but I'm dreading it and wanted to ask if there was a good way to rip it out rather than wrecking bars, cats paws and side cutters! I wanted the install work so I only budgeted $800 for the tear out but if there's a handy dandy tool I'm all ears.

I'm an old crow bar and hammer guy

But your best tool may be a couple helpers !

If this is part of a larger renovation where any dust you might make won't be a concern; set your circular saw to the proper depth and make cross-cuts every 2-3 ft. across the floor.This will make the pull up much easier as well as make bagging up the waste a simple task.
Stand on top of the floor in install stance; and use your claw hammer to pull up the boards. Your crow bar will only be necessary along the parallel walls.

Depending on the quality of the sub-floor, most of the staples should remain in the floor boards, also making the clean-up and prep much easier.

You should do well with the $800.00 allowance. One man and a grunt should handle the removal in a half day; so your only other expense will be any disposal costs you may incur.

Sounds easier than taking up a gluedown.

That's one thing I have never done. Taken up a stapled down engineered floor. Just a couple of test boards a stapled down, to see if the 1" staples were going to work in a ½" thick engineered I was installing. It wasn't easy getting up one board, but it wasn't hard either. The staples stayed in the plywood, thats where I see the pain in the butt, being. Pulling and pounding staples.

Thanks for the replies , I like the scoring idea and will definitely try that out, (I'm laying site finished Cumaru down after) so dust will be everywhere). Unfortunately I'm my own grunt so I'll just have to pack an extra granola bar or two!

use the skil saw and cut every 2 ft, then use a roofing shovel/and the 3 foot cro/wrecking bar. makes qucik work of it. 2 guys 500 feet 1-2 hrs (not including the staples )

Ditto what the other guys said. 500 ft. of 5/16" should be pretty easy. 3/4" is a little harder but not much. Those skinny staples can be pounded down. I would waste my time trying to pull them out. You will be laying 15 lb. felt over them anyway.