Why don't you buy in bulk if you were getting consistent sales ?
It worked yes, but the product prices are so high right now that isn't worth it ( due to high shipping cost ) the product is also large and i don't like that.Agree to this, it sounds to me that your products/ marketing are working, IM is all about tweaking, don't give up now.
Just stop taking new orders now, and try to figure out how to improve your fullfilling process.