Hey I bought my last car at an auction. For very cheap. Nothing to be ashamed of there!
If you had an E90 and 1 key, you would have a problem.
I have read on international forums that you can buy used E46 keys on ebay/gumtree and so on and then theres an intricate coding procedure to be followed. So dont despair.
Search the forums here, there must be something on it. If that fails google it!