Slitherine

The cost of the Regional Decision to recruit local units, in the early game at least, seems to be a fixed 100 money for two provincial grade units regardless of the unit type.

It costs 100 money to buy two Italian infantry or two Cisalpine cavalry, both of which normally cost only 30 money each if you don't already have any. Unless you really need them before you have formed the province, it makes no sense to use the recruit local unit option to buy them until the province has been formed and their price has risen above 50 money.

But in Africa you can use the recruit local unit option to spend 100 money and get a buy one get one free deal on provincial elephants, nominally 100 money each buying your first one from the province.

It gives anyone with a region in a province with very expensive provincial units a big advantage.

While true, I'm not sure it's a significant problem. The Regional Decisions can vary quite a bit in their impact depending on the region they're used in. Some of them are just better suited to be used in certain regions rather than others, and at certain times rather than others.

You've identified circumstances in which this particular decision is a big opportunity, and others where you're better off not using the decision, and I think it's okay that both exist. There are other Regional Decisions, too, that come along when I can't make effective of use of them right now.

Well said, I don't see a big issue here. Strategy is making the best use of resources and opportunities.