I bought the LM2623 from RS Components (
http://www.rs-components.com/index.html). You can buy via phone and have the materials sent via courier. I would buy only special components from them, since they are expensive.
I have one of their shop close to my home (Milano - Italy), so normally I go there myself.
The right-angle USB mini B connector is custom made by me. You need to destroy a cable to recover the connector and then, with a bit of patience and some hot glue it is not very difficult to build.
I am very happy of this battery box, which I am using by default, since the internal battery of the MT is unreliable.
The only real challenge id fixing the IC to the DIP socket. It is so small I had to buy a magnifying lens tool (cheap and easy to find in electronic shops) and be very careful in welding the tiny IC terminals to short metal leads and then to the DIP socket. It is not impossible but also here a good dose of patience is needed.
Hope this is of help to somebody
Giovanni