The typical asking rate per listing is in the $0's per square foot per year. The South San Gabriel region is going through a decrease in rates. In the last 3 months, the median rate decreased $14 per sqft per year. That's a 100% decline in rent.
In the last 90 days, 0 listings have come on the market, which means new availabilities might be going fast. You'll want to be prepared to tour spaces as quick as possible. About NaN% of the available leases in the South San Gabriel are subleases, so you will probably need to sign a longer term lease with the landlord directly. 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 sqft.