Thanks for playing and I'm glad you enjoyed it!
RE: Your caveat - Yeah this was a mechanic I deliberately built into the game - Yes sometimes they're easy to spot and only need a couple of trades, but sometimes these loops require long chains of trades to work. Each day is like a puzzle to solve - If you can find a loop and execute it you can 'beat the system' for a day by basically exploiting the poor villagers who have priced their goods unwisely. I've capped the maximum benefit you can get from the 'infinite' resources by making it so you can only upgrade your inventories once per day. You might be flush with resources one day, and stricken by scarsity the next - you're trying your best to survive in an unforgiving market that is mostly out of your control ;)