I came to the Avast forum specifically because of this pop-up. Contest, ad, free money, whatever; I'm not really happy about it.
I've been using Avast for years, and I put it on all the computers I setup for friends, family, and co-workers. I've been a huge fan and advocate. But I find any unnecessary advertisement (yes, even one for a new Avast product) spam. One spam leads to another spam. I didn't sign up for ad-ware. Countless people I've setup with Avast have upgraded to more complete versions, but Avast is going to lose me as a sales platform if this becomes a regular thing. I don't want Avast popping up information that's not relevant to protecting my computer.
That said, an unobtrusive message about this contest at the bottom of an informative pop-up wouldn't have upset me. It's popping up a message that has the sole intent of getting me to spend my money that upsets me. Left unchecked, this is the path to full-blown ad-ware. If it keeps up I will start installing another product on people's computers. Period. Too many products have gone down that road for this to not worry me.