Ok first off, big no to Buffalo Gun Center. Many reasons, just take my word for it, or google it, there are alot of issues with BGC, and after being a long time customer, I don’t recomend them.
Ok now the AR-15 platform has about 1,000 different variations. You have the military M4 which is the typical tough guy gun, and then you have the varmint. Now in NYS we have alot of restrictions, like no mags over 10 rounds unless the magazine was made prior to 94’ (sept of 94’ to be exact) it can’t have a flash hider, bayonett lug, threadded barrel end or colapsable stock.
The really easy way to be compliant is to get an accurate varmint rig, with a fixed stock, bull barrel (flat face). If you want a military style M4 you need to get it specially set up for NYS. A typical M4 look alike goes for around 800 bucks for a Rock River, Bushmaster or other, complete. You can get lower brands for less, but you get what you pay for. I will promise that if you buy it local, you will probably get ripped off. I spend alot of time working with these rifles, and they are a passion of mine. Figure out what you want, and I can tell you the cheapest way to get one.