[avni000]

Those are a lot of factors to face but depending on the sports niche and assuming that your product is superior/ well designed, then I might suggest focusing on getting a strong following with that niche and growing from that small position of strength.

For example, say it's biking apparel, I might reach out to bloggers/biking sites and perhaps doing guest features or creating something of value with them (giveaways?).

You should be able to help your SEO by creating content of value around your niche and getting links to it (organic SE rank is likely tanking just because people are getting what they need at those sites first and not bothering with smaller players). Same with your AdWords - you won't be able to compete with the massive marketing budgets of the bigger players so you'll have to be creative about using words further down the tail. Look for other acquisition opportunities by figuring out who your core target is and how you can get them to spend more (perhaps an email newsletter highlighting news/new products/trends in your niche?).

Just a couple of suggestions but hard to say for sure without knowing more specifics of what you're dealing with.