Making it clear what the costs is and making the set up ridiculously easy.
Exactly the same strategy as they did with A/B testing.
"This is always how the conversation would go:
PM: What kind of discount are you offering?
Me: We don’t discount; instead we put our pricing on our website so there’s no misunderstanding.
PM: Well I’m going to need some kind of discount. How about 30%?
Me: As it says on our website, we don’t discount.
PM: But I’m buying 400 seats!"
http://blog.asmartbear.com/startups-emotionally-draining.htm...
In addition, your product offerings keep getting better every quarter and you also want to test varying price points, offer discounts and compete well against several competitors in the process. If you are going after a market trying to acquire 1000s of customers paying $xxx/month having a transparent open pricing works great but it doesn't when you are targeting enterprises.
Disclaimer: I work for monetate and we do have a pricing page that explains to the buyers on what to expect. http://monetate.com/products/packages-and-pricing. Also, most of the enterprise buyers are used to this kind of setup and putting a price tag on your website doesn't really work.
Looks like you have some serious competition.