If you had $500 to spend on site promotion, where would you spend it? On directory listings, on text link ads? On links?
Paypal won't accept a Visa Gift Card, so paying for something via Paypal is not an option. Unfortunately, most sites accept ONLY Paypal. By the way, you're missing out if you are only accepting PayPal, I know a lot of people who won't use Paypal.
So, what do you do with $500 for site promotion?