hmm....what you're saying doesn't make much sense. niche networks charge premium CPMs (e.g. expensive to the advertiser) because they have to support their sales force and support staff. they are also generally not self service at all. adroll is way, way cheaper than a vertical niche network because it is self service. if you want to pay +$20/cpm for someone to pick sites from a list for you, definitely go with a niche vertical network. if you want a cheap self service option that has access to the same sites go with adroll.