You can seal them your self, for about $11 each.
I dont know who the Co. is, but its about $55 + shipping each, I guess it would be about $75 each. Some guys have sent them in and it didnt work, so they went back to a tube.
I sealed mine and did a writeup on page 13 of the 1300C darkside, its easey to do, read it and PM me if you have any questions.
Plus it will cost you mounting and balanceing, about $30 to $50 each, I forgot about that
The rims have holes that the spokes fit through. Spoke nipples(nuts) go on the end of the spokes to allow tightening and trueing(positioning) of the wheel. There are some companies that can seal the holes and nipples. This will allow tubeless tires to be mounted.