Great game concept I had something similar in mind but had to cut it down due to time.
My first loop I though (this shopkeeper must be crazy if he thinks I'm gonna buy two identical water bottles for different prices), so I didn't and the prices kept hiking and I could never financially recover.
My second play tho, lemme tell you, I'm what they call diamond hand cause I kept my bottles for 3 shops and sold it at 25 & by the time I had 30 shops I had 85 bucks.
Please nerf the gorilla shoper he tried to sell me red balls for 60 when it's clearly a 50 max purchase :P