I'm a professional artist who recently came across a photographer with a unique and cool style. I sent him an email him and asked if I could use one of his photos for an oil painting and what his rates were (I haven't started painting yet as I wanted to get his approval). He's fine with me using his images as long as he's properly attributed and gets 30 percent from all sales. What do you guys think of this number?
To be honest, it seemed a bit high at first, but then again, I have no experience when it comes to this stuff, as I typically shoot my own reference photos. Maybe it's perfectly normal, I don't know?
Here's an example:
An oil painting usually takes 6-8 weeks to finish. Let's say I sell it for $7K in one of the art galleries that represent me. That's $3.5K to the gallery and another $1K in taxes. Which leaves me with $2.5K. The photographer then gets $750, which leaves me with $1.75K (not a fantastic hourly rate obviously, but that's another story).
Is trying to negotiate a lower percentage frowned upon and a total no-no? I obviously want him to get paid for his work, but I want a fair deal for myself as well. That's why I'm asking you smart people as I'm pretty much clueless. I hope I'm not coming across as a cheapskate.
Thanks in advance for any advice you can give me.

