That's interesting. I assumed that the purpose of the sale was to increase the game's publicity/popularity, an attempt to get it into more peoples hands and make it into a household name. But if it's just an expansion pack, then you're really only selling to existing customers, not expanding the customer base.

The production + shipping costs were about $3 with a suggested price of $5. We also had an additional nag screen for people who put in $0.

So the free-loaders basically took $3 a pop from Wikimedia?

Not sure what your nag screen said, but an A/B against putting it in those terms might have been interesting.