na993,
This is my experienced;
Head lamp - I bought all this as a set, meaning both side left and right as a complete assembly.
Hella - RM200/pair
Hella - RM400/pair
Bosch - RM300/pair
Bosch - RM200/pair
All 4 set doesn't mean the cheapest are the lousiest. The last Bosch i bought for RM200/pair amongst the best of all.
Some pairs are from forumer here and some from chop shop.
Tail light - only one pair i bought from forumer. It cost me RM180 per pair. one chop shop did quote me RM150 per SIDE.
I think with this information, you can judge how much it should be. After all selling and buying are about supply and demand (willing seller, willing buyer)