Sounds like a day job. If you need or want a day job, it pays appropriately, etc. then... why not? If you don't, then there's your answer. This sounds like the opportunity to have a mildly creative, kind of interesting, job. It doesn't sound like something to look to for much in the way of money or creative freedom, but it sounds fine. If it was me, I'd want to take it on as a waged employee though, not on some kind of commission basis.
If it's one of those "Yeah, it'll be great, you do this & this & this & this & this, and all the other 'little' jobs we find, and we'll cut you in on our Enormous Fortune! We sell heaps! I swear!" situations, I'd suggest passing. If it falls more into the "honest day's pay for an honest day's work" category... it entirely depends on whether or not you want the work. But I don't think there's anything to fear from being distracted, or giving up some of your material, or anything like that. Do it if it's something you want to do, and you're not getting screwed over.
If it's one of those "Yeah, it'll be great, you do this & this & this & this & this, and all the other 'little' jobs we find, and we'll cut you in on our Enormous Fortune! We sell heaps! I swear!" situations, I'd suggest passing. If it falls more into the "honest day's pay for an honest day's work" category... it entirely depends on whether or not you want the work. But I don't think there's anything to fear from being distracted, or giving up some of your material, or anything like that. Do it if it's something you want to do, and you're not getting screwed over.