Always Scope first then Ammo don't buy Bank just buy it if you have too much stuffs or like own alot of upgrades it would be a perfect choice buying Bank.
Doesn't weigh anything, but you should deffo go for scope boost first and work on aiming alongside too so you can get kills very easily if you know what you're doing.
In my opinion, The scope boost is the best and after that would be the ammo boost. The scope boost does x2 damage on all scoped weapons. On the other hand, having the ammo boost does give you more ammo. Say for example if you had an EMP grenade then that means you don't have to worry about buying more than 1 or losing 1 use weapons including door charges (I think) with the ammo boost! I'd suggest getting the scope boost first though then get the ammo boost!