However, you could use a general collective noun like:
* A collection of wigs
* A set of wigs
* An assortment of wigs
You could also get creative and use:
* A mane of wigs (playing on the idea of a mane of hair)
* A crown of wigs (referencing the way a wig sits on the head)
* A cascade of wigs (if they are arranged in a cascading fashion)
Ultimately, the best collective noun will depend on the context and the desired effect.