On average, listings lease in the $10's per square foot per year. The New Castle region is experiencing a a rise in rates. In the last 3 months, the median rate increased $15 per sqft per year.
In the last 90 days, 0 listings have been listed, which means leases might be leasing quickly. You'll want to be prepared to make an offer immediately. About NaN% of the available space in the New Castle 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 1,160 sqft. Most buildings in this market were built in 1900 and are Class A.