It's important to understand the different heights available on barstools.  The "bar stool" is usually between 29 to 31 inches from the floor to the seat height, while a "counter stool" is usually between 24 to 26 inches.  As a comparison, a dining chair is usually 17 to 19 inches to the seat height. For maximum comfort, you should allow from 10 to 13 inches from the seat height to the table, bar, or counter.

The next concern is to determine how many barstools you need. A comfortable range will allow between 26 and 30 inches from the center of one seat to the next. The amount of distance allowed should take into consideration whether the barstools will be armless, backless, swivel, or stationary. You need plenty of room to maneuver in and out of the seats.

The most popular barstools are made of wood, metal, or wrought iron.  Other materials include brushed steel or acrylic.  You can typically find barstools priced from under $50 to more than $600 per piece, but expect about a 20-30% discount on eBay from the same merchants.  Because many barstools are pre-packaged in pairs, many of the pricing actually reflect two barstools.  When comparing the prices on barstools, be sure to make sure whether the price is for one or two barstools, and get a final price including shipping charges.  Most shippable barstools will require assembly, which is quite a worthwhile savings on shipping costs.