On average, listings lease in the $20's per square foot per year. The Anaheim region is going through a a rise in rates. In the last 3 months, the median rate went up $8 per sqft per year. That's a 45% increase in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Anaheim submarket has less expensive rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 40 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 110% of the available leases in the Anaheim 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,970 sqft. Most buildings in this area are around 2 floors. Most buildings in this market were built in 1982 and are Class B.