Yeah, was talking about installation, not parts
If I could find them that cheap, I'd buy all of them and become a reseller 
As for the sockets, I guess I don't understand what is different between installing a normal socket and a zwave one... is there any diff?
By socket you mean receptacle/outlet or switch? The receptacle/outlet..... z-wave or not is no different. Hot, neutral and a bare ground wire.
The switch depends if its dimming or not really.
Dimming: requires 3 wires. Hot coming in, switched hot going out to the light or load and a bare ground.
On/Off only switch: Same as above plus a Neutral wire.
Depending how the circuit was ran in your house (each light or house might be different) you may have a white neutral wire in the back of the box not hooked up to the current switch or you could have no neutral in the box.
If you wanted a ON/OFF only in a box that had no neutral then you in for a bit of work. There are several ways around this tho.
First is to determine what switch you want and where then check to see what that box has. It could be a cake walk or could present problems. 45.00 for run a neutral down a wall seems to cheap so I'm going to say that's not it. 45.00 to attach a neutral that's already in the box seems expensive.
22.00 for a receptacle/outlet seems good although I would do it myself of-course as one room could be 100.00 easy and I can do it in a few min.
EDIT: I agree with "SirMeili" I think the extra 23.00 is just to stuff that extra controller in the box.
Any reason you going with micro controllers over actual switches?
And wiring still stands... You need a neutral for for ON\OFF micro switches too, so in existing construction possible you don't have a neutral in the switch box.