ML 320 door won't open 98'

Hi, Long time looker and first time poster!!!! Just curious, planning on buying a ML 320 SUV and it has a problem with the driver side door! It will not open from the outside but will open from the inside!! Any suggestions, I want to know if this is an expensive fix, can I do this!! Is the part expensive or not!! Thanks in advance for the replies!!! BFlood

in ml 320 that I have, I got the same problem only with the rear door, it sucks that everything is hooked up to one assembly and if something brakes inside u got to change that unit, the power lock unit was about $250 at the dealers when I last checked it