Most listings are in the $20's per square foot per year. The Nogales region is going through a an increase in rates. In the last 3 months, the median rate went up $21 per sqft per year.
In the last 90 days, 2 listings have come on the market, which means listings are probably going fast. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,300 sqft.