You say you can only spend $500 on a kayak. Is that just for the kayak or
for everything you will need to go with it. Paddle, PFD, paddlewear .....it
adds up quick. Besides the Thule and Yakima racks, there are foam block
kits for about $40 that you could use to transport a rigid hull kayak. Do
some research and figure out everything you will need based on what you can
spend. Paddling.net is a good place to find out the specs and prices of
kayaks from different manufacturers, including inflatables. Don't rely too
much on the reviews on that site though. Almost every review of every kayak
seems to be a 9 or 10. Good luck!