I have tried this quest my self but I did it way too far in advance.
When I 1st did it I was level 50RDM/25BLM.
I went and bought about 12 stacks of rolanberries.
Went to the CN with a friend of my 75RDM/35BLM.
He was the one spawning the Crawler NM, so he would take the entire hate.
At that time there was a 75DRK (1st time I saw a DRK and look so freaking kool)
He help us out finishing our stack we had a lot and it was taking 4-6 of those berries in order to spawn the NM.
Well to make it short the I took home about 4 1/2 stacks of rolanberries 881.
And my friend confirmed it that it was a 1/3 rate for what he heard.
So Then I went to selbina and try to sell the berries but I did not had enough fame.
I went and farm some cabbage, (I was broke and only had less then 2k) I think it took 3 stacks of cabbage in order for the guy to talk to me and take my berries. I can't remember how much exactly he gave me but I think I lost only like a couple 100's gill's.
For me it was enough though because it gave me fame in all 3 cities Sandy, Bastock and Windy.
SO I can't say I made a profit but I can say that it was well worth it.
And in case you are wondering with the 4 stacks that I got I got fame 5.
Especially at sandy since I've done so many missions and quest that barely game me fame 2.
I think it was a fair trade.