Do you know how to make a flemish twist string? If not, you should learn how to. I used to make endless loop. Once I learned how to twist one up I've never looked back. I use D97, FF, 8190, 8125 and 452x. I've made strings as few as 8 strands for a 50 lb bow. My usual string is 10-12 strands with padded loops and double served in the center.
If you are looking for the cheapest option try to catch Chad from BCY at one of the trad events he sets up at. I load up on string at the Tennessee Classic each year. You won't beat his prices. If you can't catch up with him send me a PM next spring and I can pick up a few spools and ship to you.