You should be able to a find a studio in Washington Square West (more like $800) or adjacent Bella Vista (cheaper) for that price. Both are dense urban neighborhoods where you don't need a car. Washington Square West would be a 5 minute walk to work, Bella Vista more like 10-15 min walk with easy bus access to Curtis Center too. Not many high rises around there, if you really want a high rise you could look at Society Hill Towers which is 5-10 min walk, not sure what prices are like. Otherwise you're looking around Rittenhouse Square but you'll get more for your money east of Broad Street.
Both neighborhoods are in walking distance to Whole Foods, and close to Headhouse Square which is the site of the city's best Farmer's Market (but closed in the winter). There are also neighborhood farmer's markets all over, pretty much every neighborhood has one now, though only some are year round. Reading Terminal Market (not far from either neighborhood) is a huge year round market with a big selection of local produce and meats, plus great prepared foods. Bella Vista contains the Italian Market, a year-round outdoor market, no local/organic stuff but a great place for speciality cheeses, meats, etc. Trader Joe's is a little farther, easy subway access, but also we have two good car sharing programs that make jaunts to places like TJ's very convenient.
If you're into food Bella Vista is probably the best neighborhood in the city... besides easy access to the markets, you are close to the restaurant scenes in Center City and East Passyunk, great gastropubs and neighborhood spots in Bella Vista itself, and lots of good Italian, Mexican, and Vietnamese food.
Other neighborhoods you could consider that are a no-transfer subway rides to your work are Northern Liberties and West Philly around Clarke Park. Clark Park has a large year-round farmer's market.
Some good propaganda about the food scene here:
Philly Homegrown – Local Food in Philadelphia: Restaurants, Farmers' Markets, Shops, Tours and More
4th and Wharton Awkward Houses
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