Have a look at this:
http://www.ebay.com/itm/Eaton-GM-Fo...Parts_Accessories&hash=item1e9135f2a9&vxp=mtr
That's 2 bottles of oil + coupler for $30 + shipping.
That's 2 4 oz. bottles of oil...the other link is 1 8 oz bottle...basically, it's the same thing.
It is working the two gears and all the bearings harder in the supercharger. It's best to replace it before you need to replace bearings.
This one is only $26 plus shipping, seems pretty inexpensive.
http://www.ebay.com/itm/251577528431