Consumer goods and items consumed by the government contribute to the Consumption Index, located on your country's business page. The Consumption Index has some influence on the welfare index.
It gets a little tricky choosing what quality to buy those items at. The consumer items you purchase for your country are consumed by your population and you are reimbursed as your population purchases those items from your stock. It gets interesting where they pay an amount based on the current market price, each month, where you could have originally purchased items at a different market price.
Items consumed by the government are a different animal in that those items are simply consumed and are largely represented on your Finance page's Profit and Loss page as a cost. Higher quality items, while improving your consumption index, have no effect on the performance of various government functions and the same number of various products are
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Not entirely confused, there were some breadcrumbs I could use

thanks bro
I've also noticed that some consumer products have surplus/deficit cycles. I'm wondering if there is any way to time purchases so you get in when prices are best?
When you are getting started, you can play a bit with trying to time purchases when you find products you need on sale. As you gain cash reserves and buying power, it is possible to influence the surplus/deficit cycles to your benefit.