What sort of desk would you like? would you like one with a couple drawers and 4 legs?
For this desk you can simply detach the legs with wing nuts and take the upper section and the legs separately. I personally don't like using metal fasteners unless its absolutely needed, but these would be hidden underneath the top, and it could be broken down and rebuilt pretty easily.
Or would you want something with drawers on either side like this?
For this desk you can build the two drawer units on both sides, then attach the top of the desk over the drawer units. When moving the desk, all you would need to do is detach the top from the drawer units, then move each section to the new place and reassembled.
Whichever one you choose, it can still be built using a modular design that can be broken down and transferred to another place easily. I also don't think you need any special hardware that is designed for knock down furniture. Any one of these desks can be put together using ordinary bolts and screws which are plentiful and inexpensive.