out of stock everywhere. i've read mid-april, but i forget where. you may be able to find one with the module preinstalled though. check the partner pages here.
Digital Storm is the only place that looks like they have pre orders. Although I don't want to pay an extra $100 to have them do the install service when I'm perfectly able to do it myself.
I just want to make sure they are still selling the DIY kits.
i'd imagine just nvidia, where it's a kit for one specific monitor. i haven't seen them anywhere else, besides those partner sites, and they want to sell you the entire monitor or an install service as you've seen.
grab one when you can, not sure what availability will be like going forward. there's supposed to be a wave of new gsync monitors coming out Q2.