You're gonna love it!
Have been to Casino Point Park a bunch of times. Lots of fish, a few wrecks, some reefs - it's a lot of fun. It's gets pretty crowded on the weekends - so get there early.
I have only used the Catalina Express and it's $56.50 round trip from Long Beach
www.catalinaexpress.com but there are others - don't know if they are cheaper.
There is a scuba shop van right next to the park that has air fills and rentals if you need anything - I think they open around 8:00 AM - again be there early!!
There are also charter boats that service Catalina Island and thats really cool too.
I went on the Bottom Scratcher and Great Escape this month and they were both fun they cost around $100.00 and include your air fills and tons of food all day long.
I booked them through Sport Chalet there is a schedule on their website
http://www.sportchalet.com/corp/index.jsp?page=divers_charters
The only draw back with the Sport Chalet Charters is that there are usually some classes on the boat - so you may not go to any of the more advanced spots if there are lots of students on board.
There is a list of boats on the California Dive Boats website
www.californiadiveboats.com
My wife and I will be there too that weekend- maybe I will see you there.
Have fun!!