On average, listings lease in the $20's per square foot per year. The Temecula region is going through a decline in rates. In the last 3 months, the median rate decreased $2 per sqft per year. That's a 6% decrease in rent.
Compared to the rest of the Metropolitan Los Angeles market, the Temecula submarket has lower rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 37 listings have been posted online, which means new listings most likley are going fast. You'll want to be prepared to make an offer immediately. About 16% of the available leases in the Temecula are subleases, so you might be able to snag a great spot on a short term. 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 1,750 sqft. Most properties in this market are approximately 2 floors. Most buildings in this market were built in 1991 and are Class B.