The best place to look would probably be another charity shop!
(Tripods turn up quite often).
Otherwise a Flexi-Pod, from Jessops, might do the job:
http://www.jessops.co...ducts/16669/show.html
(See the left-hand panel for 'proper' tripods).
However it would be a good idea to check whether your binoculars have actually got a tripod bush so that you can attach them to a tripod. Not all of them have!
(If the bush is the wrong size, Jessops can sell you an adapter).
Chris