I like suggestion a and b. I don't see any balance issues from a miner/fisher perspective of doing both.
Personally, though, I don't see mining OR fishing as a viable source of zeny. Mining provides ori and elu which don't sell that fast and I use that to upgrade my gear, go me. I see fishing as providing the healing items i use when I train, though I DO tend to go through more whites then healing items now.
Most of my rare crap I sell I get from the monsters I hunt, don't look at me like that! it's true!
