Try very hard to have them put out a range of what they are expecting to pay. If they approached you then you should have some leverage in the situation.
If you focus on the value delivered, know your market (what people are paying your competition), and you can justify your higher-than-competition cost, you should be OK. Then double that, in your mind, because you're probably underselling yourself, and underestimating the cost of an employees time to even research these options [ie even the worst product delivers more value to the corp. than a continued search for a product.]
http://www.kalzumeus.com/2012/01/23/salary-negotiation/
I suspect you can glean some applicable information for your situation.