Honestly.... I would NOT buy that. Only because there's a 90% chance you do have parasites.
So what I would do... is just buy Humaworm for about 50$ with tax and shipping, and see how your body feels. It's cheaper and you might as well try getting some buggers out right NOW rather than finding out what you have, waiting a month for humaworm (because their pills and hand-crafted, made to order), and then flushing.
AND $540!?!??! I COULD BUY HUMAWORM FOR THE NEIGHBORHOOD!!!
If I had $540 I might spend it on a zapper... rather than a test kit.