Hi. I'm a bit of a noob myself, but I think I have some of this snowboard stuff figured out.
First off, with a $250-to-$80 price differential, I am willing to bet that the $250 bindings were late modeland the $80 ones were 1 or 2 seasons old.
An aluminum base will be stronger than plastic, but if everything is dialed in and tightened properly then you shouldn't notice much of a difference under normal boarding conditions. A metal base will (obviously) hold up better over time and be less prone to outright breakage.
Yeah, lots of the bindings look almost identical in function. It most cases there are only minor differences... ability to change the angle of the 'high-back', material of construction for the latches & release, range of movement of the binding straps, etc.
As they are all so similar, I would get the cheapest binding that holds your boot properly and won't flex or give out on you. My friend had some rented board/bindings that had to be adjusted twice on our trip... the loss of control made him feel less certain on the mountain. Set it up right the first time and you shouldn't ever have to worry about it again.
But I'm a noob. Maybe someone who knows more will chime in.