This is a 'deep' question. The selfish part of me would of course set the price of sbd to be the highest possible value. Then i would make a lot of money even if i don't earn much. But humans are known to take advantage so it really won't be the best for steemit. The best price for sbd is one that is high enough to help put food on the table as we know steemit is a source of income for a lot of people and low enogh to dissuade greedy individuals from taking advantage.