I would say don't get it.... A E34 is a terrific car, hell any bimmer is but like he said, don't expect gold when you pay for silver. These cars and anycar at this age will bankrupt you if you don't have some mechanic experience. Bimmers should not be cheaply maintained, when I bought mine and started to tally all the stuff I should replace I was looking at 1500 in parts alone. That's not including getting new doors and fenders. Ultimately It's your choice it sounds like you've already made up your mind.
I will say this as future advise. Never go into a car buying transaction wanting the car. You have to not want it. You cannot let your emmotions take over. It is then that you make big mistakes.
2003 GMC Sierra SLT 2500HD CC/SB