Valence - chocolate factory visits

We will be in Valence area next month - I have been told that there are quite a few chocolate and nougat factories in this area. All of them are open to visitors.

Can anybody suggest a few? I have been asked to check out Tian Armitage (hope I spelt it right).

How much would chocolates cost here? - 3 to 4 euros per 100gms? and nougat?