Replacement Dell laptop power supply

It's possible that the power supply for my Dell Latitude E6420 laptop is dying.

Dell PSUs are pretty expensive, so any views on getting non-Dell item?

I'm aware that some may not work properly as Dell seem to sometimes use some sort of sensing wire to detect and inhibit a non-Dell unit. Can this be avoided? I wondered about a Duracell PSU.

Thoughts welcome please.