Yes, you can buy used overhead projectors online. Use a comparative shopping search engine like Google Shopping to look up used overhead projectors.

Yes there are some good deals that are ending soon on Ebay for aused overhead projectors. You can also find a nice refurbished projector at www.geeks.com.

As high tech electronics are becoming more popular these days, the use of overhead projectors have deteriorated. More people are using "Smart" boards or "E" boards. The use of overhead projectors are slim to none.

because projectors are big and if it has a lot of stuff to show on a projector then it will have to use a convex mirror to be able to see all of it...

You should learn the difference between CRT, LCD, and DLP overhead projectors, and know which kind you need. Look at the portability, brightness, and contrast ratio of the projectors to find one that suits you best.

Any of the chain office supply stores in Pennsylvania, such as Office Depot or Staples, will sell overhead projectors. If they don't have one in stock, they will be able to order it for you for store pick-up. With non-chain or smaller stores, it may be more difficult to find overhead projectors because their stock can be more limited than the national retailers.

The best places to find an overhead projector in Pennsylvania, is to go to a chain store such as Staples, Office Max, or Office Depot. These stores will either have overhead projectors in stock or they can easily order one for you for store pickup.