But also be aware there are some real winners on ebay such as these counterfeits. My last time buy parts from Intersil had 0049 date codes so I wouldn't trust anything newer than about 2001 or so. CA3081s should have RCA markings up until about 1990 (taken over by Harris in 1988), they should have Harris logos until 1999 when this product was spun off to Intersil, they should have Intersil logo for a brief period of time in 2000 before they were discontinued.
There are also some signetics SG3081s out there but they're not real common.

There are some valid ebay parts out there but be aware of parts like these that were supposedly made in 2012 - long after Intersil discontinued them.

CA3081_Maybe (resized).jpg

Unlike the eleleparts, those posted by jj44114 look quite reasonable. Proper date code, proper part number marking (there should not be an "E" suffix shown in the marking on that era of parts), and for those made in 2000 - there is an "MALAY" beneath the intersil logo (for Malasia). Those look almost identical to the leftovers that I have from when Intersil did their last time buy.

CA3081_Probably (resized).jpg