Door Mechanism Faulty?

[BH14]

Hello,
My front passenger door wont latch. I've inspected the lock mechanism and when I close it with a screw driver, it will spring open after a few seconds. I'm assuming the lock mechanism is faulty and needs replacing. Am I right? Can i purchase off eBay with confidence or is it best to purchase through a dealer? Any advice is appreciated.

 

[krusing]

Cheaper at a wrecker,
approx $20 > $40, depends on the wrecker.
My drivers door lock was faulty, purchased a S/hand one at a wrecker, $30,
Being the cost of a new one from a dealer at approx, $300, and if my s/hand failed, and I purchased another s/hand one, I would still be in front.

 

[BH14]

Cheaper at a wrecker,
approx $20 > $40, depends on the wrecker.
My drivers door lock was faulty, purchased a S/hand one at a wrecker, $30,
Being the cost of a new one from a dealer at approx, $300, and if my s/hand failed, and I purchased another s/hand one, I would still be in front.

Thanks krusing.