Yep, that's about right. Actually, the tach sensor board is about 1/4 wide, and I could just put two of them on one design to make the size. Add a cut line in the middle and you just hack it in half. Six of the PCB's that way would probably cost you around $1.75 total, and they ship free. For that price, I normally order several orders.
One bonus of doing your own board and soldering the sensor is you can get it the right height. Many times I have to unsolder the sensor and reposition it.
