You are looking at an extremely competitive niche and a very small budget - and this means you have to be 'super extreme' creative and careful on how and where you spend it.
SEO: To be utterly honest, even if you ad another 0 to your budget, it's still pretty difficult to invest in SEO and get good ROI unless you are going after the narrow segments within that niche i.e. long-tail (geo, etc)
PPC: I assume Mortgage related keywords cost you $5-$20 for every little click and your budget will run without having any data. Meaning, budget is not big enough that you could run a PPC campaign and know if the campaign was successful or not as you will run out of $ before you blink.
Others: If I were you I'd take that budget and go on the Guerilla strategy and do lot of forum promotion and genuinely try to help people and do classified ads - being careful not to "overdo it" or do any kind spam. Watch Yahoo Answers and see if people have any questions about what you're offering and answer them.