You are going about it all wrong. If you don't need it, sell it. Make money. Produce high priced items and ONLY sell un-needed FINISHED items. ie.. don't sell cheese, but sell pizza. Expand as you go. In other words, once you can expand, do so, right away. I have only 110 storage and have a population of 1.5 million with 720,000 simileons. When building/upgrading you should always purchase the over produced/selling items and produce yourself the items required that you rarely see on the market. One more bit of advice, when in the market, click on anything if the item you need is not displayed as more often then not, I purchase most of the items I need when I am going to as many cities as possible.
Good Luck