This is from Peter Aspden’s FT ten point guide to mastering the contemporary art market:
So you quite like the look of something, and you ask how much it costs. “Two,” may be the reply. The air of vagueness is a test. You will know, from your studies of the artist in question, whether that means £2 (no), £200 (unlikely), £200,000, or £2m. But if the gallerist’s assistant is American, she (almost always a she) may be talking dollars. Don’t ask. Make a rough calculation in your head that covers all possible options. Any physical reaction is ill-advised, other than the barely perceptible raising of an eyebrow. Finally, ask if she will accept roubles. You’re on the front foot now.
Keep in mind that art sellers very often have preferences over the quality of buyers they sell to. Higher quality buyers lead to referrals, perceived gallery quality, and also do more to boost the artist’s reputation, which in turn helps the value of the gallery’s inventory.