This is an excellent restaurant. Christophe was our server and he was wonderful. Our French is non-existent but we try. Christophe was very patient and helpful and we really felt he was pleased we were dining with him. Some places we have been, the servers seem a bit put off by our lack of French.
Anyway, the food is unique and clever. We just had pintxos, no main dishes. I would say that 8-10 will do you fine. 12 tops. Add a bottle of wine and with tip you'll spend between $150-200.
Do yourself a favor and read about the very unique Basque culture before coming. It's not super traditional, but the menu certainly gives a nod in that direction. Don't miss the basque cod and the venison. Definitely my favorites.