Seattle-based Redfin, the online real estate brokerage firm headed by Glenn Kelman, said Thursday that it has arrived in Philadelphia, the nineteenth market for the firm. The expansion into the City of Brotherly Love is its first market expansion in over a year. Redfin explained that it took the firm over a year to expand into Philly, because it's "hard to figure out" a model which works in a city like Philly, where average homes sell for $182,000. Redfin's model has been proven out in much more expensive markets, such as San Francisco, where the company said homes now average at $894,000. The company did not say how it figured things out, but that the key was figuring out how to deliver great service and still pay agents good money.