I emailed them.. it's per Piston. The "kit" is because it includes rings, locks, pins... The guy referred me to a dealer though who said he could do $550 shipped if I purchased a set of rods with it as well. Pistons alone would be $575.
Would you guys trust ebay for something like this? Not ebay quality parts, but an ebay listing. This seems like a pretty good deal to me: