You can get an idea of how much you can spend on specific pieces by looking at the prices they have listed. The the Artwork Archive's Discovery platform, Artsy, Artspace,
1stDibs Platform, and many other options are only some.
Don't ask for an unwelcome discount or take out the gallery
It's fine to negotiate prices - up to a limit.
Major collectors and museums are generally entitled to 20% off or more. Excessive haggling will reflect poorly on you and may earn you a "do-
It is not advisable to list your methods on the "not to promote" list if they seem rude or aggressive.
You should not try to avoid galerists and buy directly through an artist you represent. The artist is in a difficult situation.
This could put at risk their professional relationships as well as damage your reputation among dealers. This could negatively affect your ability to sell your work.