Buying RF metal shields
On Farnell they found by searching for 'Screening Cans'. Most of them are from the brand PERANCEA. I got some of them as well, they seem to work fine. Make sure you order them and fit them on your PCB design before you sent out an order to make dozens.. 

It might require some fitting before you want to be sure to get them designed in. What I mean is that the ones that have a removable lid might be a bit larger from the drawings. The case itself folds over itself within the case, making it twice as thick as shown. On wrong measurements, it might also mean you end up with a screening case that is slightly rotated to make it fit.

If you search for 'screening' (at farnell) you might also find metal strips that you can place on PCB's as 'dividers'. I don't know what Digikey or Mouser has to offer, but I suspect they might have more. Screening, shielding, all EMC terms should give good results.

However, I do know distrelec has got many items under the search result 'screening'. They also got SMD mounted screening cans etc.