Expensive mistake mate, but at least there's no chance of you making it again, now you have a spare. ;-)
You didn't happen to ask how much a new key is for an E36 318i did you?
There's a guy over on M3cutters that's spending a FORTUNE on an E36 M3 Cab, bought it rough and replacing loads of parts on it to bring it up to A1 condition. Each to their own I suppose. My point is, he only paid £40 iirc for a new key for his, where does the extra 90 bangers go??? Alarm part of it? As the E36 only has a wee light on it...