Check with CKS- we take trade ins on boats, so we often have some used boats for sale. Our largest selction is during swaps and at the beginning of the season. Right now I have a Waveport X in great condition for $250. Its about perfect for your size. Call the Salida store if interested at(719)-539-2920. Ckeck the BV shop at 1888-CO-KAYAK for other used boats we might have.
Also, you save 15% on accessories (helmets, paddles, etc etc)
when you buy a boat here, so its a great deal for someone who's just starting out (or anyone really).
Everyone else is right, the buzz's gear swap i the best used boat resource for CO.