On average, listings lease in the $30's per square foot per year. The Waterfront submarket is going through a a boost in rates. In the last 3 months, the median rate increased $39 per sqft per year.
In the last 90 days, 2 listings have been posted online, which means leases most likley are going fast. You'll want to be prepared to make an offer immediately. About 50% of the available space in the Waterfront 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 360 sqft.
Not much of the real estate is used for commercial space, so it might be hard to find office space. Wholesale trade is the dominant industry in this area. Most of the folk of Waterfront work from home. Commuting close to 10 minutes a day is the norm for those who opt to reside in this part of town.