I was notified by newegg that it was in stock, but now is currently out of stock 4 hours later :/ Is there much of a difference if I went with the non-OC version instead and decided to manually overclock it?
Most OC cards are just stock cards that were binned slightly higher so were overclocked in factory. There's a very good chance you'll be able to overclock a non-OC card to the same level, if not more.
Llunai is correct on both accounts factory OC use the higher binned cards ergo better quality and "normal" cards could be usually clocked to the same rates most of the times. But I'd use what he said to look at the other side of the coin, factory OC cards can take higher clock-rate and generally a better product that can be overclocked manually even higher or at the very least have leas wear off at that kind of use. Is it worth 10$? That for you to decide.