If you can’t afford to commission an artist, don’t tell them that their prices are too high. This leaves the impression that the artist’s work isn’t of value to you, which can give them a bad impression of you, the client.
Instead, say that you are currently unable to pay for the commission, or that you would like to get back to them when you can pay. Don’t devalue an artist’s work just because it’s out of your price range.
Art is created by people, and those people are the ones who determine their own value. Respect that.