It's just a name, if your idea is really that great, just make up a verbish type name that doesn't exist and use it.
"I believe that a good domain name is an important success factor in building and launching consumer web services. It's not in my top ten but it could be. It's certainly something we think about a lot when making investments and working with companies post investment."
Check out his article to read his reasoning.
This is an example of where a bit of knowledge can be dangerous.
$500 also doesn't pay for a professional naming service. That can cost upwards of $10k, sometimes much more because it gets bid up by people like P&G who need new names all the time. You can always rename and buy a better domain when you become successful enough to afford it.