Help finding upper

[jray707]

Im lookin to get a 50 beowulf upper to go to an ar15 lower. Im lookin to find the chrapest possible, used doesn't matter. Anybody point me to a site or an ad or something pls? I'd be willing to settle wh an ar10 upper but gotta see what i can fjnd for 50 first. Im new to buying and building for personel use so pls understand