Why not just call on people in the traditional ways?
Buying leads for a SAAS seems a bit absurd in so far as nobody has ten years of data on SMB's buying SAAS products. And nobody has more insight into your potential customers than you.
Yeah, it's hard work and it won't scale from 1000 customers to five million customers worldwide overnight. Scaling anything from 1000 to 100000 will require completely new systems across the organization anyway. And that's a good problem to have relative to never getting to 1000 customers.
Generally, the best thing to do for sales is to get out of the building.
Good luck.