it's not so hard. hopefully someone who lives near you is good at it. i've taken it completely apart and put it back together again twice. what's kinda funny is that the first time seemed to be easier (or maybe i just got frustrated because i expected the second time to be smooth and it wasn't quite).
the white/red one i got off ebay was pretty cheap... looked pretty good and had all the nokia markings, but the material seemed kinda off and the red part felt bigger than the oem one. but it did come with all the parts and a t6 screwdriver too.
on a side note, anyone using the ad-41 with their n73? i got a cheap one off ebay, it worked once and then proceeded to break. i was wondering if there was a reliable seller out there for those.