I'm in the middle of this right now for my first can.
1. Go get your trust.
TexasGunTrust.com can do CO trusts also. He was super helpful.
2. Set up an online account at silencer shop. Between the website and the app, you can do everything except the fingerprints. It's not easy to navigate, but it's all there.
3. Once that's done, find a kiosk and do your fingerprints. The local shop I used didn't care that I wasn't using them for the transfer, and they didn't know anything about how to use it. It takes a week or so for Silencer Shop to verify your trust. They contacted me because my scanned trust was illegible, so I had to resubmit it. Once they're happy with it, they'll send you a form to Docu Sign.
4. Purchase the suppressor at any point in the "paperwork" process.
The fees add up. If you buy online and transfer to your local shop (SOT), they'll tack on a $100 - 200 fee transfer fee . . . plus the cost of shipping. That may offset any savings that you gain from an online purchase. You'll pay ahead of time for the "stamp." The local shop charged $245 for the $200 stamp: something about a processing fee.
You might check out
Mile High Shooting. The seem to be priced on the low end for the can I just purchased, and they're just north of DEN. I see they sell Surefire cans, not sure if they have or can get the specific model you want. I haven't purchased through them, so I can't speak to anything else about them.
Cheers,
David S