Over the past several years, I've used a variety of coaxial cables and even more connectors to complete my antenna experiments. My best source of coaxial cable has been my neighborhood cable TV installer, who often has suitable lengths of RG-59 / RG-6 cable after a major cable installation. I've found RG-59 and RG-6 (73-75 ohm impedance) a good substitute for 50 ohm RG-58, RG-8, and RG-8X coaxial cable. The mismatch isn't too great, and an antenna "tuner" can make the cable suitable for dipoles and inverted Vs.
The only negative side of RG-59/RG-6 is the need for F connectors and adapters to convert F connectors to the common SO-239 found on many coaxial cables and transceivers.
In this excellent tutorial from "Helpful DIY", we get a complete guide to installing F connectors--something that could help you get a decent coaxial feed line at little cost.
Here's a brief explanation of the process involved: