I believe that you also can buy an adapter to convert your 18v to lithium. DEWALT DCA182 2 Volt MAX Battery Adapter for 18Volt Tools | eBayDeWalt is switching over the the 20v lithium battery tools. 18v Nicad batteries and tools will be supported but are being phased out. So it is not surprising that some 18v deals are going to be popping up. Look at any of the big box stores and see how many 18V tools you can buy. They are getting rare.
Doug in SW IA
I bought my 20v a few years ago at Lowe's... 2 batteries a charger and the drill for $100. If I get anything else it will be the bare tool, then I will pick up a couple of 5 ah batteries.