The short version
7 companies supply this market — a reasonable cushion if one runs into trouble. The generic price has fallen 93% in a year, to $0.7711 per unit — and generics that get this cheap tend to get abandoned rather than defended. The brand (Xigduo Xr) runs $19.18 per unit — 25× more. Put together: this looks like a healthy supply — the boring kind, which is exactly what you want.
The numbers behind every sentence are on this page below — and the Watch button emails you when any of them move.