After googling ford explorer lift kits, I can tell you than they run from $200 for 2in to upwards of $700 for 6in. It all depends on the company and the quality of parts.

As for installation I personally do not know, but I can guarantee you there will be a few tuts on youtube.

Personally I think it's pointless to lift a 2WD vehicle. It's pointless because a lift is supposed to help with off-road capabilities, and 2WDs suck at off-road. But just take it down to any body shop really and they can give you a quote on how much they can do it for. If you're wanting to do it yourself then online they run $200-$800 for lifts, but installation would be more difficult.

A 2x4 doesn't really need a lift kit haha, but hey, I'm 4x4 and neither do I, but I did it. I did a 5" lift, the kit costed me about 1k, and I did it myself with a couple other guys, so labor was about 250. (I asked the guy who sold it to me how much he would charge, he said around 650-700).

Do not lift a 2wd their is no point in doing so.

That price range is obviously for a body lift, which are extremely ugly and leave a gap between frame and body. If you want it to look good you are going to have to get a suspension lift which is much more pricey.