Yeah, this rush is pretty crazy. You have to hawk the website daily. The "Wishlist" feature isn't even working. I just happened to see that rifle a couple of hours ago, placed the order, and thirty minutes later it showed out of stock. The guy I'm doing my FFL through is a State Trooper and he wanted to order one when he called me back, but it was already out of stock. Crazy!
Quantico tactical has rifles in stock, if you feel like paying more than Bud's. They stamped "Don't Tread on Me" on the magwells. Looks pretty good, but their prices don't justify it IMO. Especially for the M&P-10, where they list "Our Price" at $1650 and "MSRP" at $1610.