(which is a very awesome indie game in its own right) has multiple methods for people to buy it, but I prefer Steam, because Steam is pure awesome. I think Saira was made in MMF2, but I'm not sure, though it definately has Steamworks integration, so it can be done in Construct. Steamworks is really awesome, you can update the game whenever, have achievements, in-game dashboard, Steam Cloud etc.
Oh, yeah, and free advertising, don't forget about that.
If Valve thinks your game is awesome, and is perfectly willing to let it onto Steam, they'll probably be willing to help out with Steamworks integration.