I am a relatively new user of cordless tools, having bought an 18v set a few years ago and since then added a few other tools. I have 4 off-brand aftermarket batteries that I have been using, two from when I first bought the set and two more that I bought about 18 months ago when I bought the house and had no power on site. I have used them hard, and some of them are getting a bit weak. It would be handy to have a couple more anyhow, as I keep adding tools. What I am wondering is whether I should just get the cheapest ones, or whether it's worth paying a lot more for the DeWalt ones, or if there is an aftermarket brand that is better than the others. I know these tools are pretty outdated, but they work great for me, and I am committed to keeping on using them for as long as possible. I'll be grateful for any advice.