Especially the adventure games, does anyone still sell them?
Three I have in mind 25th anniversary, judgement rites and final unit. CD versions all.

eBay is probably your only option. Last retail re-release I saw was Starfleet Academy on White Label and that was years ago. I think Voyager Elite Force was re-released on the Xplosiv budget label as well. You can probably still find Star Trek: Legacy in retail stores but without mods and an Xbox360 controller it's fucking awful.