After The Slums, your items don't get returned. There are areas where gold and items can be found. These areas include but are not limited to the sewers, the cave west of the farmgirl, alicia's basement, etc. (alicia also offers gold from working for her).
I've taken the gold difficulty into account, and future updates that are now in early release include a gambling NPC. The easiest way to proceed would be to leave a lot of gold/items unobtained until after the Slums. However, playtesters and I haven't experienced the difficulty you are experiencing. I will try to look into what I can do to make this easier.