Two of my regular stores still have them, but you're right, they're getting rare. In all my hunting throughout the panhandle last week I found High Roller at very few places.
Bring on the Bens is going that way too, along with Lucky Red 7's and Big Money. I saw these at maybe one store in ten.
High Roller I probably saw at one store in twenty. Flamingo is about the same.
Monopoly Park Place Payout and Lucky Loot are starting to dwindle as well. They're a little more frequent than the others, but they won't be for long.
All of these games have a top prize left (two in the case of Lucky Loot).
The $5 game that perplexes me right now is The Price is Right. Two $250k prizes left and yet it might be the rarest of the bunch (with the exception of the Shimmering 7's). I found that ticket almost nowhere. My guess is that it just didn't sell that well and retailers simply stopped ordering it.
I think the best buy at the moment in the $5 games [aside from Shimmering 7's if you can find them] is Flamingo. Comes with a bonus of the ticket being rather pleasant to scratch. It seems like there's a lot of wax between the cardboard and the surface material so it scratches off smoothly. The polar opposite of $200k A Year for Life which you need a dremel and a cutting disc for.