Not sure about Groupon but FYI a well-targeted list usually goes for about $60-$80 CPM for a single mailing.
Yeah, they're that valuable.
Re:Groupon’s Success Disaster
by espadagroup on Thursday September 16, 2010 @03:17PM
(#1698798)
Thrillist charges $200+ for it's email ads.
I haven't priced that kind of a service and on the surface it sounds pricey. However it may in fact be much cheaper than some other mediums with that type of each like radio or TV ads.
You could always advertise using google local which would be much cheaper, but something tells me that being the groupon deal of the day is a much more compelling proposition.
I guess I agree, it isn't a bargain but it's probably not the worst investment considering the the alternatives.