I used to make my own recurve strings (I've always been pretty good at handicrafts and stuff like that and have nimble paws which helps) but get my compound string and cables from Greg Hill- see:
Greg's String Specials
For compounds he also installs the strings too, which really helps those of us without room/cash for a bow-press, especially as he uses an X-press which can take the parallel-limbed bows safely too.
It always surprises me that folks will spend a fortune on bow/arrows/gizmos and not get a decent string. When you look at the time and effort that goes into making a decent stable string, no wonder it's an area where manufacturers compromise, OEM strings CAN be OK (eg Bowtech) but often better replaced ASAP. At least IMO anyhow
Besides, a custom string set can look really good too- and I enjoy the aesthetics of a nice-looking bow/kit set-up.
Finally, as "any fule nows" of course, PINK STRINGS SHOOT BETTER!
P.