Yeah, now the challenge is just that I don't remember the exact amount :-). I believe $20k or $30k. We'd raised ~$1.8M by this point and so it seemed like a reasonable amount to spend.
The domain owner initially asked for $30k. We negotiated him down to $12.5k up front and another $12.5k a year later. As an early-stage startup, this structure was a huge win, since we expected we'd either raise money or no longer exist within the next year.