Unity3d Ps3

How can i make games for the ps3? When I go to buy unity, there’s no ps3 add-on, only for flash player, ios and android

Actually, Sony is VERY welcoming to Indie developers. Much more so than Microsoft or Nintendo. If you get in contact with them, you’ll probably be able to get a license with them pretty easily.
You just need to show that you know what you’re doing (have a plan, show that you’ve done work, etc). Having AAA titles developed by you isn’t a requirement. However, currently: You’ll probably only be able to get your hands on a PS4 DevKit.

I’m currently working with Stratos Gaming, a small indie company that has had some contact with Sony (This and the fact that the ps4 DevKit is supposed to be among the most user-friendly and API-dynamic to use, is where i get my information from).

Also, unless you get a special deal with Sony (which happens more often than you might think), a DevKit costs $10,000 ~ not $20,000. Correction, currently a DevKit is $2000. In 2008 the price for a ps3 DevKit was cut in half (from $20,000 to $10,000). Then in 2009 the price was cut by %80 down to $2000.

And as a little side note: I would wait for the Ouya to come out. The ODK is free, and is built on the Android OS (Unity will compile to this).