kirkd makes some excellent additional points. And, just to be clear, even without knowing the OP, I can also tell "his heart is in the right place." Nearly every starry-eyed 'hobbyist' who spends enough time doing A/V recording for bands/artists beyond basic fan-taping, however, will eventually either burn out on 'working' for free and want to get some compensation, or will come to build up resentment about (perceived or real) expectations from the bands/artists absent some acknowledgment/compensation of the time and effort put in doing professional services pro bono (whether or not actually being an 'amateur').
Having been the 'audio guy' for numerous video shoots, some paid and some unpaid, I've learned some things. One of them is that the artists/band managers, etc. usually have almost no idea how much time and work goes into audio or video post-production for these types of 'jobs.' Another thing is that artists/bands, who are mostly very poorly compensated themselves, will often heap on expectations of professional quality results and turnaround time without acknowledging that they may be receiving hundreds or thousands of dollars worth of work for free. What they do know is that equipment is much cheaper and more accessible to amateurs these days, and that presents them with opportunities. So, there's an awareness that they can take advantage of amateurs to try and get professional quality stuff without paying for it. Promises of possible back-end compensation are always empty absent a contract. (Open taping situations are clearly different)
My advice is that the OP should put more value on his own time and services, considering the 'professional' type of 'work' you're doing, and be very clear with yourself about whether or not you find some other value and/or are interested in 'working' for free. I'm not saying do not 'work' for free; rather, I am suggesting it's better to not delude yourself about possible back-end compensation, and that an audio and/or video recordist should be honest with him/herself about it. If you like the artist/band enough, and are willing to undertake essentially professional work for little or not compensation, that's cool - do it. You're getting some value out of it for yourself then. If you're doing it with the hopes of maybe, eventually getting pay and/or recognition, without a solid promise/contract, it may not be worth the time and effort in the end and the relationships may suffer. To ask someone else to join you in all that as a collaborator is asking a lot.