Rental costs if we rent tanks including ean32 is normally 13 dollar per tank per day. So then you can say 50 dollar for tanks, 20 for entrance fee, but the rest?
I think EAN32 is generally overkill as most cenotes are shallow. The only cenote I've exceeded 45' - and I've been in 7 or 8 different ones - was Pit. And it was too deep for EAN32 at 132'.
If the guide is independent he probably owns the tanks, and if he works for a shop the shop surely does, so the tank "rental" is just internal cost accounting but still revenue.