One of my players asked me the limit for cyberarm strength. I have no idea. In the main book it just says you have to start paying essence after 4 extra points, but is there a hard limit, other than essence?

M&M pg. 33

"...a character may not possess a cyberlimb with a Strength Rating higher then twice his Body, or Body + 4, whichever is lower."

Any strength enhancements above 3 cost .4 essence each still, don't forget the nuyen cost too. If you are thinking about Alpha grade or better, remember that the strength enhancements must also be alpha. (the strength enhancements are part of the arm.)

It also mentions that they already come with a base strength too. So enhancements would add to that base.

If you don't have M&M (Man and Machine). I would stick to the essence rule. It's simple and it works.