[mtmail]

Look at the value you create, not the cost. In SaaS margins of 90% are possible if remove your time in the calculations. In B2B the decision maker has the same work with getting approval, adding you to their supplier list, dealing with their accounting department or filling out forms for $5 or $50. I'd even argue per-seat price model has disadvantages because the invoice amount might change month-to-month and requires additional re-confirmations of the customer's accounting department. Start with a higher price (be confident), you can always lower later or offer (time limited) discounts. $5/month is zero when you have to deal with 1-2 support emails, the first 12 months is zero when you have to do one Skype sales call.

Lots is written about SaaS pricing, it's complex. https://www.priceintelligently.com/blog/ has a decent blog on that topic (and free ebook I seems).