My Friends Say My Boyfriend Is Money Hungry

My boyfriend is an artist and be sells his art. My friend really likes his art and asked him if he could design a tattoo for her. He said sure. She wanted this really big tattoo design of a women. Kinda mother nature themed, with water colors. He then told ger it would be 150. She was surprised and said "You're charging me?" He said "Yeah, art isn't free. Its my job. She then starts to say she's been my friend forever, since before I even met my boyfriend. Not sure why she brought me into it. He said "That's great. Still 150". She got really mad at left. She later texted me saying my boyfriend is money hungry and he doesn't like art. Just the money... I ignored her. I don't believe my boyfriend was wrong to charge her. Art takes a lot of time. But then she is my best friend. What do you guy think?