There are places to get cheap banquet chairs. One place is www.wholesaleweddingchaircovers.net where you can get them as low as a couple dollars a piece.
There are many places that sell banquet chair covers. A popular place is called "The Knot". You will find a variety of competitive prices and colors available to choose from.
Yes, umbrella chairs, inflatable chairs, etc....
Yes, Ebay.com does sell office chairs. There's a manufacturer called Spider Office Chairs that sells them. Here's the link (http://stores.ebay.com/Spider-Office-Chairs).
No they do not, but Office Depot does sell Herman Miller chairs. They have a wide variety of office chairs to choose from. http://www.officedepot.com/a/browse/chairs/N=5+501503/
Best Buy does sell mesh office chairs. They offer several colors and brands. Chairs are available online or in stores.
Walmart
Only the Kroger stores in Kentucky sell it.
Simmons Furniture does sell single dining chairs. Simmons Furniture has a large selection of chairs for different purposes, which can be bought as a set or individually.
Staples does sell ergonomic office chairs however their range is not that large. These chairs are available at similar prices, and sometimes cheaper, from stores such as office depot.
Many department stores sell bedroom chairs, however Walmart, Target, and JcPenny would offer the cheapest and best quality(for the price) bedroom chairs.
No, Target.com doesn't carry banquet tables. They do carry folding picnic tables but they are small, for 4 people. You can try homedepot.com for banquet tables though. They sell for $199.