Here is my submission:
I wanted to do something that prevented cleaning up your cards. Originally, this didn't clean up any cards (including your hand) but then I realized that was too strong. This can work well with while in play effects (highway, groundskeeper, etc.). This works best if you're not drawing your deck every turn. Also when critiquing, note the downsides if you play this before a reshuffle (all your played cards miss the reshuffle).
To preempt people from saying that this is too strong compared to Outpost consider this: If you get a deck that can work with outpost (guide, or a well trashed deck) you can effectively double your turns for the rest of the game. If you have a deck that can draw settlement every turn then settlement doesn't provide a great benefit, since all your played cards can't be played again. If you can't draw settlement every turn, then while it will give you extra turns, it won't double your turns for the rest of the game.
update: changed cost to $7