A. The user is not technically savvy.
B. The user is only going to play Farmville or extreme Texas Holdem or games like that
You aren't going to save any money building your own system. Depending on the game/application, you will probably not have any real world gain by building your own system, and you have a higher likely.
Most users do not and should not need to build their own system unless its a hobby and you are prepared to deal with any tweaking you will need to do down the road. Just because it can be done, doesn't make it the best option for everyone.