Can we negotiate with a gallery?
The collector @raph_is answers your questions and sheds light on the art market.
Absolutely! I never saw a deal cancel because I didn't ask for a discount! Always try, these are mostly important purchases. Also don't expect to have more than 10% which is the most common figure. Otherwise it means that something is probably wrong.
There are other factors to "amortize" your purchase:
Free delivery: delivery prices increase quickly, it is always better to negotiate it before.
Payment deadlines: paying in several installments (even if you have the total amount in your bank account) is always advantageous and can allow you to keep cash if you have another purchase to make in parallel.
Negotiate more works: some galleries offer a 3rd drawing if you take 2 for example.