You ain't going to find it no cheaper, don't worry about this, "What does this discount entail", if they told you then they would have to take you out to the wood shed :thumbup: :thumbsup:
The discount is about $150 off the usually $550. Here's an old form, but the prices are still current. You can order direct from Glock and have it shipped.
I have my eye on the new G20 gen 4, I may cash in on this soon.