Since Hank Parker's show with the kayak fishing, kayaks are a hot item. There has been ESPN coverage of several Kayak only tourniments, also. Recently, I have seen some good deals on used yaks, some barely used. Folks tend to rush out and buy, get tired, and then sell or worse yet let the yak just sit around.
I believe any "fishing" kayak should have a rudder at the very least. The rudder will at least help you keep the direction you want on a drift with out using the paddle. As seen in this and the other pics posted, I also carry a set of wheels to get the yak from the jeep to the water. Most lower priced yaks are kinda heavy and it's easy to rig at the car then wheel to the water.
If you plan on fishing with a bunch of rods and tackle, a milk crate is nice. I can, but don't usually carry 6 rods fairly safely between the rod holders that came with the yak, plus two more in the crate I modified and the two RAM rod holders I installed,6 or 8 "beverages", and plenty of tackle. I haven't caught any real big fish so the Wally World freezer bag will keep most fish at least cool for a couple of hours.
As seen in the pic below, I use a V type sail. It can be purchased ready made for under $300 but, I have seen plans on a forum some where that tell of making the same type for around $60. Depending on the type of rudder you have, this sail will sail slightly up wind. I use the sail for trolling sometimes, and eating and drinking most of the time while going to other spots to fish.
One last thing, plan on leashing every thing you don't want to lose if you're any where where theres a chance to get out of the yac by some choice other than your own, don't ask
except seacats 
