I've bought lines from both Russ (okie air) and Melvin (MBS.) In both cases, I've been quite pleased with all aspects of the result: quality, price, service.
These businesses tend to be small, often with one control line competitor as the driving force. As such, it's not a bad idea to establish phone contact before placing an order. Last week I placed an order Monday evening at MBS, which was delivered Thursday morning, making the Kansas to Virginia trip promptly via USPS. So, now I have 1000' feet of 7-strand .015, eyelets, connectors, a prop for the NVCL trainer, etc.
One thing I like about the Okie Air offering is how flexible the length of lines are. For example, I can order 150' or 300' of line.
Peter