Got the tracking working in the end. Turns out it hasn't left Bremen in Germany yet, and was only collected from the warehouse today (I got the eBay 'Dispatched' email on Sunday!).

For any one else who's trying to track their laser cutter and finds this thread, you need to select 'Logistics' (instead of the default 'Express') tracking from the DHL homepage and then 'Road and Rail Freight' Tracking and enter the supplied tracking number as a 'Package ID', and it will only show anything after the package has been picked up by DHL.

To answer Boyan's question, for me the most 'useful size' is the biggest one I can afford, and will fit into the workshop. The size and laser power isn't too important to me at this stage, as I'll be cutting small parts from thin plastics which should be fine with even an entry level machine.

However, If I need a more powerful laser in the future, then a new tube and power supply could be shoehorned into this machine (with perhaps an optics upgrade at the same time). On the other hand, if I needed a larger cutting area, then I doubt any upgrade would be practical.