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.