How can a plug cost so much?

We are rearranging the kids room and using some bookcases give them some privacy.  Since they are going to be in the middle of the room and not against the wall we are connecting them to each other and to the wall at one end.

We need to drill through the bookcases to connect them with long bolts.  We can do this.

At the bottom of the coat closet is a tool box and we have a Black and Decker Pivot Plus.  It is simple rechargeable drill.  We also have a set of bits. This drill is currently for sale at Target for $29.99

But I can't find the power cord.

Can't buy it at the local electronics store.  "I could fit a plug in, but it might be the wrong milliamps."

I got to the local hardware store.  I thought the would have a universal plug for Black&Decker. "No you should try Radio Shack"  I walk there, "Yes we have something for you that might work and it costs $35"

No.

So I went back to the hardware store and bought a real drill with a cord for $40.