Worldmaster one row

[dunnp]

Hi there,
I just picked up a one row Worldmaster in basically new condition in the Barras Market in Glasgow. It seems to be single reeded and the stops seem to be fake though I haven't spent much time with it yet. The bellows look cheap but seem airtight. The whole thing has barley a mark and it looks almost new. I assume Worldmaster is a type of Weltmeister. For the experts about how old is the box. I paid twenty pound. Is that a bit much? It plays nice enough though not fast and I keep missing the buttons because they are smaller than I am used to. Any information on these type of boxes would be great? thanks in advance, Patrick