RageCams offers all gopro authentic replacement parts for all hero cameras:
Here is the lcd readout screens:
Hero2
http://ragecams.com/shop/gopro-hero2-readout-replacement-part-p-596.html
Hero3/3+
http://ragecams.com/shop/gopro-hero33-readout-screen-display-part-p-685.html
Hero4
http://ragecams.com/shop/gopro-hero4-readout-replacement-part-p-774.html
gopro lenses:
http://ragecams.com/shop/advanced_search_result.php?keywords=gopro+lens&x=0&y=0