How to find an email marketing expert?

We have a product that some buyers really like. currently our only marketing approach is to spam to scrapped email addresses. (yes, we are shamed of but it's the most cost effective method we've tested). the good news is that the spam report/complaint ratio is very low, 0.03%. the bad news is the conversion ratio is also very low, under 0.1%. my questions are: 1, will an email marketing export be helpful? will they insist to send legit receivers? will it be an excuse to have horrible result, charge us tons of $$ then leave us struggle? 2, where to find them? any place that we can simply hire and pay without worrying too much about the skill level, profession ethic, etc.? 3, what's the fee level involved? we are willing to pay by performance + small base fee. what's the standard payment scheme? thanks!