Welcome to webmaster world.
Now the owner has a reason to keep it, "cuz you want/need it".
If you want that domain domain, than you can try:
1) wait for few days till it is dropped (or for few months)
2) register the name when it becomes available.
or
3) I think the owner might still have like 30 days to renew it... ask him to renew it and pay even more money (I would let it expire and use below services to grab it)
Now if you really care about the name and you kinda seem to be willing to pay 500 bucks for it.. I would advice you to look into
Pool.com
SnapNames.com
GoDaddy.com
NameWinner.com
As these are 4 good domain snap service (I say pool is # 1... cuz it generally wins the best domains)
Again good luck with your domain hunt.
NS