Planting an Herb Garden

Today I spent the morning planting a container herb garden.  I've planted herbs before with moderate success, but this time I actually purchased a book, did some research and put some thought into what I would plant and where.  I am limited to containers because I live in the Spring Valley neighborhood of Washington, D.C., where chemical weapons were tested in World War I.  Our lot has received a clearance from the EPA, but I still don't plant anything that we would eat in our soil -- why take chances?  

I'm not sure whether it is cheaper to buy fresh herbs from the grocery store on an as-needed basis or plant them myself.  I spent $88 buying 18 small containers of herbs (if you must know, it was 2 each of arugula, basil, cilantro, mint, parsley, oregano, sage, rosemary & thyme), a small bag of organic fertilizer and a large bag of organic potting soil.  Luckily, I already had the clay pots.  The chives pictured here have been going strong for about 3 years now.  

I don't have much hope for the cilantro.  Apparently, you have to remove and plant new cilantro plants on a monthly basis throughout the summer.  I use cilantro pretty often, so I am not sure it is worthwhile for me to try to grow it, given my limited space and the herb's limited harvest time.  I may just buy from Whole Foods and start freezing what I don't use.  Anyone have any cilantro advice? 

Resources:

• Miranda Smith. Your Backyard Herb Garden (Pennsylvania: Rodale Books, 1997).  Good directory of the most common herbs, but the book assumes the reader already has a basic knowledge of gardening.  
  
• American Plant Food Company - selling small containers of herbs for 20% off during the month of May if you are a Garden Rewards Member.