Is this used colloquially the same as in English, to indicate the price of something too expensive?
Interesting question since it's a bit of an exaggeration of the cost :-D and every language/culture has its unique way of doing that - in French "ça coûte les yeux de la tête".
My thought too! In Italian it's nearly the same as the French, "un occhio della testa", 'an eye from the head'. Surely the Gaels have their own quirky expression?
The only thing I've seen so far is something that translates to 'it's as expensive as gold'
In Portugal we say that also "custa os olhos da cara!"