I think that will be fine if you put some kind of visual indicator, that shows the relation between : g of Product beeing building / g of Product beeing selling. For example, an arrow under 3 counters (top-right) with 3 states: 1.- green: you are building more than selling. 2.- you are building the same than selling. 3.- you are selling more than building.
After a long farming, I managed to improve two rings until level 30 (max HP and HP regen.), and there seems not to be reflected in green levels. I think a redisign is imperative.
I think this physics-game has great potential. Keep working hard at it and, sooner or later, the fruit of your efforts, will your well-deserved recognition.
It's a good concept, but needs improvement, keep working, you're on the right track! I found another bug: the pet does not heal when you rest in 'Traveler's Den'