Yes one of those ones from best buy. My friend has had one for about a year but he decided to play bass and is willing to sell me his guitar for about 50 dollars.

I was thinking of swapping out the pickups, tuning pegs, nut and whatever else is neccecary to make it a decent guitar. (and maybe attach a bigsby or a maestro if I can find one.)

Do you think it would be worth it to buy and upgrade it, or should I save my money?

(Concerning my funding: I've only got 300 to spend and I'm only willing to shell out 150 for a guitar+upgrades. The upgrades for the SG will be a gradual upgrade process.)
I don't even shred
You can put a **** in a tuxedo, give it a fancy car, a nice house and make it damn eloquent. But its still a **** trying to talk.