Goodman Marcus,
If you merely wish to peddle your wares to commoners, a sweet treat will likely earn you anywhere between 5 copper and a silver. There are plenty of fine bakers in Wayside given that the country is the breadbasket for the continent. The cost of materials plus 15-20% is a good rule of thumb.
However, if you wish to cater to those with deeper-pouches, two major factors influence genteel tastes: prestige and eccentricity. Even the most banal wine from the canopy of the Leaf Crown can draw 15-20 gold per bottle due to rarity of the vintage. Similarly, I've heard tell of a mushroom found in the depths of the Vornae empire which, when harvested at the proper moment and combined with the right ingredients, can augment the body with preternatural strength. If your Monkey Bread (an unfortunate name given the Kin community in this region) has rare ingredients or protective qualities, it can be sold at an upcharge.
Barring that, timing is always a useful tool. Adventurers in specific are prone to upspend during market weekends. The Spirit often flags during late-night escapades but can be reinvigorated with hearty food. I have known simple crushed nut and berry sandwiches to sell for 3 gold and more during particularly grueling melees. A canny merchant can take advantage of adventurers who often have more gold than sense and a penchant for spendthrift.
Steward Dramthin Hartsboon
Keeper of the Tainted Grove