There are a lot of factors that have to go into this.
A) Which console? You didn't really specify a console. It sounds like you're asking about an original Playstation.
B) Where you get it from
Just looking on Amazon, these are the prices I found:
Playstation 1: $17.95 used
Playstation 2: $40.00 used
Playstation 3: $144.95 used / $189.99 new
Playstation 4: $319.99 used / $399.99 new
Of course these prices are subject to change depending on when and where you get them.
Game prices always depend on the game, but the Playstation Store prices are not often below retail.
9.99 at the Playstation Store. The game must be purchased from the Playstation Store is it is one of the PS2 classics that have been developed to be playable on the PS3
It is not available on the PlayStation Store.
Amazon has it for $18 for the game disc and $39.99 for the Playstation Store download Code
They are free to download
$20 As of 8/1/13
Escalation sells for $14.95 at the PlayStation Store
It is free with a new game or must be purchased with used games at the Playstation Store see related link
It is $15 from the Playstation Store
$29.99
Do you mean the Playstation Game Medievil
It depends on which PlayStation it is (1, 2, 3 or the portable one) plus the cost of each game.