The best place to see Clarsach harps is at one of the summer festivals of traditional music:

14 - 16 april: St Jean du Gard (30) Festival Boulegan à l'Hostal
13 - 16 july : La Châtre (30) Festival « Le Son Continu » (ex-St Chartier)
September : Ceret (66) Festa del Joglar

And maybe some others in between...