The ad network business is very crowded, the margins are getting lower and Google is crushing it in display ads of late.

There is very little room for new player in this space, and the players who have reached scale are very well funded.

Ad Networks will be a 'winner take most' market, and I do not suggest trying to play in it unless you have:

a) deep pockets b) some amazing technology that is really innovative and groundbreaking c) a disruptive business model d) massive domain knowledge (which you just said you don't have).

This is not the best beach to surf IMO. Any niche you've found that reaches any kind of scale will be taken by the bigger players who have hundreds of sales executives each.

The opportunity for bootstrapped ad networks is long over.