Morning guys, I use a small electrical cable roll. The black round plastic thing that building wire, earth wire comes on. It works good because it's free from any electrician who would usually throw them out, and also because you can stick your arm through it and just throw the anchor over and let it spin off.
It is probably a little bulkier to store on the yak than a kite winder thingy.
I just saw this diver's reel on a US forum. Looks the biz, made for underwater with an integral locking mechanism, comes loaded with line. I'm not sure if they're available over here, there's a mad keen diver at work, I'll see if he's seen them (probably not at US$34.99 unfortunately).
Have been using a 200 mm piece of pool noodle for some time, just wrap the anchor cord around it. Have a clip tied onto it to attach to the yak. I only use builders line for the rope and a reef anchor made from 10 guage fencing wire which has 6 prongs on it. Seems to hold pretty well in weed etc. If I want to leave it I just chuck it over the side, floats you see!
Also carry a ski stock with the basket removed which I shove into the sand in shallow areas, it has a 3 metre cord attached which clips onto the yak. Carry it in the spare paddle spot on the side of the Outback.
Very handy to fend off rocks and sharks and to reverse with in the shallows.