There was an agreed upon group buy over a year ago posted to the Tesla Model 3 Owners Club - Vancouver Facebook Group on Sep 20, 2019 for two options ranging from $1501-1719. That said, I’m sure there have been learnings since then so specs and install may have evolved since then, not to mention whether your SR+ comes with the same speakers just not hooked up. But yes, just ask for David who seems to have dealt with the majority of us.
Also, there seems to be many DIY options now available on the Internet for US$80 if you’re just looking to activate a few of the existing speakers (without a sub or additional amps). But this involves a few hours work on your part to install.