Maxell 4x + or - RW 15 pack $6.99 @ Office Depot

http://www.officedepot.com/ddSKU.do?level=SK&id=274784&cartEntryId=6

In store and on-line. There are 30% coupons available from Best Buy that OD is reported to accept, bringing cost to below $5.

Correction:

+RW: 4x (RITEK004)
-RW: 2x