Think you had a great buy there fella.
I've repaired over a hundered cars and in all honesty can say that beemers are one of the toughest out there,strong as hell,I'd guess there was nothing more than light panel stuff on them,don't forget the front ends gonna be the thick end of £2000 from a dealer with rad pack, clips,lights,fog lamps etc so take painting,labour,re gassing aircon etc it soon adds up and could easily write something off without recieving much of a hit.
Starting to think about these myself now,I was having ideas of a focus st but these do seem ridiculous value.