I actually had the same query last year when I pushed a place I work at to use a combination of Yahoo! Pipes and Zapier for our Facebook postings. I asked for a smaller plan (we only need about 600-700 zaps/month at the most) and was just instructed by their support to utilize their reward program[0] which offered an extra 50-100 zaps/month based on what you 'complete,' and it included things like (IIRC) liking them on Facebook or following them on Twitter.
It seems like that program has since been limited, however, as it now redirects to a referral page[1] only. A combination of a couple referrals around the office and performing the required tasks gave us about ~650 monthly "zaps" at the time and we haven't needed more than that so far. Still, I would have happily paid $5/month or something to avoid the hassle (and be able to pay them for their wonderful product).
It seems like that program has since been limited, however, as it now redirects to a referral page[1] only. A combination of a couple referrals around the office and performing the required tasks gave us about ~650 monthly "zaps" at the time and we haven't needed more than that so far. Still, I would have happily paid $5/month or something to avoid the hassle (and be able to pay them for their wonderful product).
[0] https://zapier.com/rewards/
[1] https://zapier.com/referral/