Hi Timz,
I started to try to answer your question about costs, but there are too many variables for me to get anything like a good single rough number for you; the biggest ones being the location(s) and operators you choose, gear rental and dive guides-- it depends on which operator you choose and how comprehensive the gear rental. I have all my own gear including tanks and I don't hire dive guides so I don't have any personal rules-of-thumb. Force E has a few store locations, and importantly they have a shop in Riviera Beach, so here's the gear rental pricing for them as a reference:
Gear rental: https://www.force-e.com/equipment-services/gear-rentals/
A half-day trip on Narcosis dive charters in Riviera Beach is $65-95 depending on tanks and whether you dive air or nitrox
Scuba Diving West Palm Beach Florida with Narcosis Dive Charters
You can find descriptions of the West Palm Beach drift dives on Scubaboard and on the operator web sites
Narcosis ... and the other West Palm Beach drift dive operators in my experience ... will put a diver in the water to guide the dive and carry the line-and-float, and that's included in the basic cost of the dive charter. The drift dives in West Palm Beach are relatively deep (70 - 90 feet).
Accomodation in the Riviera Beach area can be had for ~~$100/night
If your friend from Orlando is supplying the car, you can expect to need gas on the order of $100 for the down-and-back plus whatever running around gas you need.
To make the trip less expensive, there are beach dives in Florida, but most of the diving in south Florida and the Keys, it seems to me, is from boats.
If you travel further (from your Orlando starting point) to the Key Largo area, you will pay more for gas and it will obviously take longer, but you will have more choices for diving. A half-day 2-location trip with Conch Republic will be $85; Conch Republic has a "boat package" gear rental at $35/day.
Conch Republic Divers
Most of the Keys operators do not put a dive guide in the water unless you arrange and pay separately for the guide. But the Keys trips will have lots of choices for great shallow reefs, but you need to check the trip descriptions carefully as there are a lot of Keys trips to wrecks. Accommodation in Key Largo will likely be more than the least expensive you can find in the West Palm Beach area, but there are lots of choices you can find on the internet to explore.