I think it might be important to add that symbio site owners need to keep in mind who their customers are likely to be when setting up pricing.
I try to ask myself what I would pay for this image and set my pricing accordingly.
IMO I believe it is next to impossible to determine who our customers will be, what they will buy, or for how much. Even on agency sites there is no way to predict who our customers will be or what they will purchase.
Once we venture out on our own via Symbiostock our possible customer base likely increases many fold - who can possibly predict who will buy what and for how much?
Photographers are the harshest critics of our own work. Use sales histories, agency price calculators, and other on-line pricing tools such as fotoQuote to provide pricing guidelines. Googling "stock photo pricing" will provide possible resources for pricing. Not gut feelings of what I "think" my images are worth.