The folks at Mermaid are reasonable.
http://www.scubadivers-aruba.com/index.html

The dive sites are here:
http://www.shorediving.com/Earth/ABC/Aruba/

There are many good boat trips, I have not had a bad one!

We have prescription masks and bring our own fins, so we are abnormal.

We used the boats for the first year and use at least one a year for places not approachable by car.

Good Luck, Pete