On average, listings lease in the $30's per square foot per year. The El Monte region is going through a a rise in rates. In the last 3 months, the median rate went up $31 per sqft per year.
Compared to the rest of the Metropolitan Los Angeles market, the El Monte region has smaller rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 3 listings have been listed, which means office spaces are probably leasing quickly. You'll want to be prepared to make an offer immediately. About 367% of the available space in the El Monte are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,080 sqft. Most properties in this region are around 2 floors. Most buildings in this region were built in 1974 and are Class B.