They're negotiable to the degree that the expenses are negotiable.
The big-ticket items in an HOA are typically insurance, utilities, elevator, janitorial, landscaping, maintaining a gym or pool, on-site staff . . . . and, as James points out, if you don't have enough money in the reserve fund, then you're vulnerable to special assessments every time a light bulb needs changing or you have to shovel snow.
So, no, you're not going to get the HOA to say, "For you, the fees will be less. Everybody else, we'll chip in a little more."
All the best,