What is affordable to you? That means different things to different people...
I recently had been testing out the Epson 3010 and 5010 and liked both of them. The 3010 (now 3020) is plenty bright, shoots 3D, and is not expensive.
As you can see from the replies, you will get ideas all over the board. If you can narrow the question, that will help.
Do you want 3D?
Are you a gamer?
Is there lots of ambient light in the room?
How far from the screen will the projector be...