How can you have a marketing budget and not a marketing strategy?
How long have you existed? what data have you collected? what worked and what didn't? Whoever you bring on board as a marketing expert will ask you these questions (if he doesn't, you don't hire them.)
If you're just starting, you need to ask "who did we develop this for"? Then go where your supposed clients are. The simplest thing you can do is use Adword's Keyword Tool to see how sought after your keywords are. Google your product description and look at the top 20 competition websites. Analyze the sites and see what language they're using, collect synonyms, different phrasings and popular descriptions (all done with firfox plugins, btw.) Then search those keywords in the Keyword Tool.
This will give you a bird's eye view of how your competition is spending its Google advertising money (you will see them in the ads on the right after you search.)
You now have enough data to form a rudimentary strategy.
The fact that you like this skill in-house is not very reassuring. No one you can hire will care enough about the product to put in the grueling research hours necessary to make your product a success. You might be better off forming partnerships or joining a CPA program; at least the scalpers will push your app for a commission, though they might drag your brand through the mud in the process.
If it's your job to spend the $3k, please don't throw it away just to seem like you're doing something. Get a marketing person on retainer + commission, skimp on the retainer but go heavy on the commission; that guarantees they have enough incentive to come on board and go for the long run. Pay their early commissions with little fuss, and maybe pull in some multitier incentives (though all of this could be avoided if you developed the talent in house, and pushed your product like crack, with solid quantitative data in hand. Otherwise your marketing strategy is "Pay and Pray".)
Good luck!