Buy a high quality, comfortable PFD and a good helmet.
Buy a good paddle.
Borrow a friend's old river runner kayak (old, not ancient
) and get on the water. Learn to roll, find your edges and balance and have fun for a few weeks or a month (assuming you'll be doing it frequently) just being on the water. Start demoing playboats.
Your skills will progress VERY rapidly your first year. A boat that will feel edgy at first will feel awesome at the end of the season--so buying something radical and starting in it is going to be frustrating. Buying something boring is going to help you learn faster--but you'll never use it again once your skills outgrow it. Borrow your first boat, buy used your 2nd, buy the exact new boat you want for your 3rd.