If you haven’t already, stop talking about what it took to create it and start talking about how much value they’re going to get out of it.
Figure out how much time / money it will save them. How much that is all worth. Tel them your software is less money than that.
I have the luxury of knowing I have the best product, but even if you don’t, you can’t give in to the hardball shit. Play hard to get instead. Dare them to go buy the cheap thing and let them feel like you know they’re making a mistake and you’ll see them in a few months when that doesn’t work out. It pays to be cocky in those situations. It starts to make them feel like you must know something they don’t.
It’s the only way. (I sell one of the most expensive software products there is, with loads of cheaper competitors)