My Impact with One Purchase

I have been thinking a lot about this factoid that Local First-type organizations speak about: approximately 45 cents of every dollar spent at the locally-owned business stays in the local economy vs. 13 cents spent at a national chain business.
I recently purchased a pair of shoes from my favorite indie shoe store. I could have easily bought the same shoe at a department store or--heaven-forbid--online. But, not only do I appreciate the friendliness of this businesses, the sales people are knowledgeable and spend the time you need with you. I tried on a few styles and hemmed and hawed as I tried to decide between two pair. In the end I choose my new $100 sandals in brown.
It is very convenient that my purchase was nearly exactly $100. That means $6.10 went to the state capital and $2.00 went to city hall to fund basic services. And, according to the statistics mentioned above $45 of my purchase stayed in my community through paid wages and purchased office supplies, marketing and advertising dollars, etc. If I had bought the same shoe at a big box shoe seller only $13 would have stayed in the local economy. That's $33 lost.
There are 600,000 people in my community. Let's say half of those make a $100 purchase of shoes, clothes, or electronics a month. If 300,000 people make that $100 purchase at a big box store my community loses $9.9M per month! Is that correct? Whoa, what an impact one person can make!
For those who have a penchant for online shopping, try keeping those tax dollars in the state. Unless, of course, you want to have to put out your own fires and haul your own trash to the dump. If 300,000 people in Tucson redirect $100 of online shopping a month to stores in town (preferably locally-owned stores) we'd keep $600,000 in the city coffers and over $1.8M in state coffers in just sales tax revenue. Per month. Over a 12-month period, that is well, a lot of money. My figures are conservative. All it takes is less than half of the population of Tucson to spend $100 a month at a local business instead of a big-box or worse an online store to keep the economy humming.
In a state with relatively low property and income taxes, we really need our sales taxes to fund basic services such as police and fire departments.
Let's not give the state more per dollar of our hard earned money, let's just keep it local people!