I'm pretty much a newbie around here, but I just found what I think is a great deal on RG59 coax.
It is Belden YR23930 75 Ohm RG59/U DS3 coax. 20 AWG solid copper center conductor, 95% tinned copper braid, plenum rated PVC jacket at .242 OD. There is a company out of Las Vegas selling this through eBay. Or you can do like I did and buy it outright from them for $100 (includes shipping!!) for a 1200' wood spool.
So far as I can tell, (I have not made any long runs yet) it works great, and at less than 9 cents a foot delivered the price is right!
BMS