Yes, those Strad posters are excellent.
Also, you can download lots of postcard size images (including Slava, Du Pre, Bylsma,& others) here at the ICS photo archive:
http://www.cello.org/oldics.htmI suppose you could mount and frame some individually, or make a poster sized collage of several of them.
The other idea might be to search out old publicity images / programmes (Ebay?) and frame them . They would be larger, and when mounted and framed even larger still.
Of course if the music swap shop idea ever gets off the ground you might find other teachers willing to swap similar materials................

* EDIT*
That link doesn't take you straight to the page. From that Home page you need to click on 'Library' in the left hand menu. A page should come up with a pic of lots of books as a heading. Click on the book which says 'photos ' and it should take you the right page. Those images can be enlarged.