On Gumtree is an AVO MK II valve tester for sale:
http://www.gumtree.co.za/a-antiques-collectables/edgemead/antique-valve-radios-amplifiers-+-rare-avo-mark-2-valve-tester-in-mint-working-condition/1001532722040910011146409
http://www.gumtree.co.za/a-antiques-collectables/edgemead/antique-valve-radios-amplifiers-+-rare-avo-mark-2-valve-tester-in-mint-working-condition/1001532722040910011146409