Marketing is about figuring out what channel best works for your business and then scaling it up (what Dan said). Unfortunately, you cannot outsource this, until you have figured the channels out and chosen a few to focus on. Once done, you can then get someone who has experience in optimizing that channel and scaling the campaign up efficiently.

Adwords is amazing for validating your idea, but with the increased competition, it is becoming too costly if your LTV is not very high.

SEO takes a very long time (three years) as your domain needs to build authority. I would not bother about it at all, till I achieve product-market fit.

Look for other channels that your competitors are ignoring - channels like forums, or facebook ads, cross-promoting with a complementary product. Spend a fixed amount on each channel - say $500. You can then figure out which channel works best for your business.

As an example, for my self funded business, I did all the marketing and dev work for a year and a half. I tried adwords, facebook & twitter ads, buying banners on various relevant websites and forum postings. Once I had figured out the channel that converted the best (in my case forum sales threads), I hired someone for doing all the work in that channel.

If you want some suggestions on channels which might work, don't be afraid to mention your business here.