While shopping for a new hdd, spotted a few cheap laptop batteries in the webshop's sales corner (leftover inventory?). Took the gamble and added a pack that -according to specs- should contain 6x 2600mAh cells.
Pack turned out to be
totally dead (0V), so it probably sat on the shelf for a loooong time. But I was able to revive the cells (details in
this thread). Don't have exact numbers, but runtime tests showed capacity
in the neighborhood of what's specified for the cell type. Sadly I was unable to find
any clue about the pack/cell's production date. Not even through IC markings...
Long story short: 6 pcs. 'old' (?) but unused Sanyo UR18650FM (spec: min. 2500 mAh) for Eur 3,33 a piece - not too bad I think.