Anyone know a website that sells the least expensive m16a1 complete upper? so far ive found only one place that has these in stock and they were charging $310. If someone could find me a place that sells these for less thatd be great. im looking to buy one so later i can buy a complete lower and slap it together into a retro-esque plinker but i want to get one of these uppers before they're gone and the ones left get super pricey