...you might want to consider a used kayak. Five hundred bucks isn't much to work with (and whatever your first kayak is, it will be the wrong one :). It's easy to sink $500 into just your paddle and PFD (okay, so 'sink' was probably a poor word choice). You really don't want to go too cheap on your gear. It's the stuff that keeps you from feeding the fish (along with a good skill set).
And someone (well me in this case) will surely suggest you sign up for a kayak intro class. You will learn bunches.
Heel and Pegpads™
The Kayak Wing
Pull-Up Strap Handle Kit
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