i'm not sure if guitar connection does this. i don't really deal much (or at all) with guitar connection though.
zen would be fully capable of assembly, but i don't recall them dealing in guitar parts.
besides, companies like warmoth deal direct. i don't think warmoth hands out dealerships... so i could imagine why stores wouldn't bring in their parts.
it's not too difficult to order the parts though, then you would have the choice of it being assembled why whoever you got them from, or assembled here