Deleted

Yeah, they've put that up in 2012, and I think I may have gotten my copy during a shorter offer period even before that.
Edit: I didn't even bother looking closely at the link. Does look like the official page got taken down at some point.

That said, the OP may be asking because the games are already listed on Steam, which is admittedly rather odd at a glance. GTA1&2 used to be available through the GTA Complete Pack, but that package was was pulled when Vice City got removed for music copyright issues; Since then (and despite Vice City's return to Steam), we've had the GTA Collection available in its place.

That is not a legit site

please, remove that link