Subi's are piss easy to work on, apart from wiring anything from a Liberty will fit an Impreza if you could find a cheap fucked WRX it's easy enough to swap everything over, really depends on how much you like the car you have now and how much time you want to spend, Pickles Auctions are best for bargains but you've gotta get it to Gerro, I've done it a few times and minimal tools are required, I think if you found a 2L you'd be disappointed after a few weeks and a 2.5 "might" be a wiring problem, personally I'd stick with what you have or get a different car, like they said above, pretty cheap these days.
This is the type of wreck you'd want to buy.
01/95, Subaru, Impreza, Wagon - Pickles Auctions Australia