Not sure if it's possible to get $300k on $20k/month revenue, though.
Basically you need a small-scale VC or large-scale angel investment... or else to continue to bootstrap.
If you don't do a series A the valuation of the sale of the company will be taken. A sale without investments in between would mean a debt investor only gets his money back + interest.
Given your situation, the debt investor might negotiate a time limit for the conversion (and either a cap or a formula for the valuation at that point).
Email me, and I'd be happy to discuss your situation and provide pointers where I can. (address is in profile)
You'll likely need to part with 10-20% equity in the business, but the value of the $300k to take you to the next level should make sense. Think of it as - can we get to $200k/m by 2012 if we have $300k/$600k/$1mm. If you can 10x your revenue in a year and give up 20%, you're in a good place.