I'm a reseller of ESET Nod32 its pretty easy really someone asks for X amounts I pop the figure in an excel spreadsheet and back comes the price.
I've just quoted a 15 User for 2 Years when the customer emailed "Can you do anything on the price? We've looked at some Internet sites and can get it cheaper". Getting the hump as usual I mailed back asking if they could provide the URL so I could look into it, to my surprise they mailed back saying it was ESET's own site!
Now I'd quoted £444.40 however they had a price of £433.20 when I checked my price matrix I found they was right and I was wrong.
Mind you fancy moaning about £11.20 But yes even I get it wrong sometimes.