I usually shoot about 2 rounds of sporting clays ($55) or 1 round of clays and a couple rounds of skeet ($30 + $6/ round)
So, about $60 or so
if you have a vest or thing to hold shells that would be useful and you'll find that helps a lot. I have a few spares I'll bring.

eye and ear protection obviously.

Bring at least 200 rounds, I'd just buy a flat (250). There is ammo for sale on site. I'd suggest #8's for all around use and 1 oz loads if you can find them. (recoil is cumulative and 1 oz blows up clays just fine)