part of the problem with DD pups is they are only based on a small handful of real SD pups. And they aren't based on really nice ones.. they are fun of the mill. I think in the DD line there is a copy of the distortion, the jazz, the standard single coil and maybe a paf. You'll get a lot more variety with another company.. or just getting real duncans.
Armstrong pups aren't super cheap, so it's not like you'll save a bundle. I've found GFS pups to be a lot less than even armstrongs, at least for the humbuckers.
If you want something different, save up for a set of Rio Grandes.. like a set of BBQs or something..