Which ps3 should I buy without having to worry about memory depleting or overspending? ?

please keep in mind that i do not want to spend too much on a ps3. I am considering buying the Metal Gear Solid edition 40GB, but i am also concerned if the amount of memory will suffice. I mainly want the ps3 for gaming, so please omit the storage of videos, pictures, and music when considering if the amount of memory will be enough.