I was listening while at the AGM and don't recall hearing any donation suggested. They did mention a few times that there were contribution boxes available.
I think the original NWT was done to match their theology with bible verses and some of the videos they showed especially the Herd "Trip down memory lane" interview session with old timers said how they would read verses that didn't match with their knowledge because the scriptures were inaccurate. Once the NWT was release, those scriptures then matched JW theology.
All bible translations get revised from time to time. Their cheaply produced versions were the source of complaints and they realized they needed to produce something a little better when it came to the Bible. All the hoopla surrounding this was a marketing ploy to increase contributions. They could have announced the release at the district convention (which I'll bet they wanted to have one ready but it must have gotten delayed) and made it available 10-1. But inviting everyone in the English world to the AGM and creating a buzz certainly produced more donations than if it just been made available at the literature counter.