I went down a rabbit hole on the mid-race course changes and wondered how they moved the buoys:
The cheapest ones go for 5k per mark, but they are quite shitty, they have a single propeller and not very powerful. In 25% of cases, they will make a mess
The first decent ones go for 8k/pop, they have 4 propellers and are more powerful and they have inertial guidance for when GPS fails/they lose contact. They might make a mess in 5% of cases, but usually in really bad weather that is also covered.
The AC ones are probably in the 25k/ mark. Huge numbers for sailing clubs, chump change for the AC.