When I look at the steam store Portal has a price tag of $9.99.
Portal didn’t come out until 2007 with the orange box, which also had hl2: episode 2 (and tf2), but the base game of hl2 came out standalone in 2004. This giveaway is a celebration of hl2’s 20th anniversary, so maybe they’ll do a portal giveaway in 2027.
They’ve admitted to cancelling ideas before, getting to various stages of production before going back to the drawing board, but always (and appear to still) insist that it is in development on some level. That’s why Newell’s responses to questions about hl3 are usually some form of “we have nothing new to share.” Valve doesn’t like sharing until they’re in the final stages of development, and hl3 has never made it that far.