Say you had a tech product that could be applicable to a various verticals like Healthcare, Financial, Education, Insurance, Manufacturing, etc... and you decided to ramp up your sales. Would you look for VARs that are already in these spaces? Or would you hire a sales rep who has some experience in these verticals? In either case, how would you find VARs or sales reps who are experienced in these verticals?
The New York Times had a good article on this topic last month - here's a link.
I'd suggest you focus on one vertical first - pick the one where you think your product offers the most value.
For leads on VARS and possible sales reps, I'd look at industry groups in your target vertical, see who is tweeting and blogging intelligently, and I'd ask your clients and prospects about the VARs with whom they have positive relationships. You can use LinkedIn for leads on sales reps and look on job sites such as The Ladders and Monster.com.