On average, listings lease in the $30's per square foot per year. The Arcadia region is going through a a rise in rates. In the last 3 months, the median rate went up $37 per sqft per year.
Compared to the rest of the Metropolitan Los Angeles market, the Arcadia region has greater rates, and you'll have to negotiate above asking rent to be in this hot submarket.
In the last 90 days, 5 listings have come on the market, which means spaces most likley are going fast. You'll want to be prepared to tour spaces as quick as possible. About 300% of the office spaces in the Arcadia are subleases, so you might be able to find a shorter term or below market rent. 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 1,420 sqft. Most properties in this market are around 2 floors. Most buildings in this region were built in 1984 and are Class B.