There are a number of anti-fouling paints that work well on Delta cruisers.
Our boat is in San Joaquin River fresh water most of the time where it is kept in a slip. I've had good luck in the past with just Interlux Bottomkote. Pettit Trinidad is the favorite of several area boaters I know.
The boat was bottom painted in October with a professional anti-fouling made by Sherwin-Williams for the shallow draft trade: it was picked with my wooden boat and usage in mind. It's a semi-hard antifouling paint. As a bonus, the untinted color looks good with the canvas, too.
Controlling algae and other plant growth is the primary job for bottom paint on displacement speed boats in fresh water. Not as many marine critters as salt water. Most copper-based anti-foulings can be wiped clean by a diver if the boat is infrequently used and when the paint is over a year old and less effective. Not necessary, though if you use the boat more often.
There are moves afoot to ban the use of copper anti-fouling on California boats. The need for the ban has not been established and I don't think any prohibitions have been passed yet. Non-metal antifouling paints may require frequent cleaning. Back in the old days, lead was the most commonly used metal for anti-fouling paint.
Boatyard custom is to charge retail for materials (including bottom paint). That's the way it is and I wouldn't try to haggle over that. If you want to bargain a bit, it's best to do that on the bottom line estimate. I like just a verbal estimate and agreement. I've done most of the work on the boat myself, so if I don't trust the guys I hire to work on it, we wouldn't be doing business in the first place.