A corollary is that your SaaS product needs to be priced in a way that enables sales (typically >$5K ACV).
The lower your price, the more your product and sales process needs to be self-service, because you can't afford to send a salesperson out for a $1000/yr contract (airfare + hotel + rental car + their time, annnd you're over any possible return, even before including R&D and support costs)
http://saasaddict.walkme.com/getting-your-saas-acv-annual-co...
Armando Mann over at RelateIQ uses Cohort Growth to measure LTV for each customer within a cohort to ensure the business is growing taking into account the bottom line.