I really prefer to go to overstock.com because they offer cheap, name brand products at a low cost. Plus, most large items come with free and fast shipping.
You can either spend money on chairs to match the table or you could look into redoing the chairs you have to match the table. You would save money if you redo your chairs. Just decide what you want to spend on it and find the store that has the chairs, if you choose to buy them.
Staples does offer ergonomic chairs, but there are cheaper places to buy these items. An example of such a website is http://www.officechairsoutlet.com/
Lightweight chairs are always great and don't typically cost a lot of money. You want to make sure it also has some form of arm rest and a back to the chair.
An affordable company to reupholstering restaurant chairs is called IMad. It is located in Wisconsin but I dunno where you live.
I would recommend lazboy furniture as a regular customer have the most comfortable arm chairs from my personal choice.
Depending on your preference, here are so far the best place where you can find and buy wrought iron chairs at: - www.PatioFurnitureUSA.com with different styles but with much higher price, OR; - www.nextag.com where wide selection is available at affordable prices.
Someone can buy all black chairs online at Amazon. They have a variety of items, including chairs. Therefore, someone can buy all black chairs there.
There are a couple of online websites that sell boardroom chairs. The best website to check out would be Office Chairs. They have a lot of chairs in stock and they are at an affordable price.
There are various places where affordable foldable chairs can be found online at auction houses or the outlet or sale area of online shops. Plastic foldable chairs will probably be cheaper than wooden oder metal chairs and usually can be found in bigger supermarkets like Target or Walmart.
You should look for a party rental center. They carry needed things like chairs.
You can always buy additional chairs for any set seperately from the manufacturer.
The most affordable Aeron chairs would probably be found as Sit4less, they are refurbished (pre-ownd) or have just been put together and there for not in their boxes. Another place to look would be ebay, a lot of Aeron chairs can be found there at good prices.