Klipsch puts their big-box lines on sale frequently, finding those for 25%-50% off new isn’t unheard of. The price seems in line for for a used pair would cost. If buying in person just take a good look at them first, if they look real they al ost certainly are, I can’t imagine there’d be much of a business case for building convincing Klipsch RP fakes.
If you’re buying online and having them shipped just pay with PayPal (and request an invoice to do it officially vs the ‘send money as a friend’ option) and if they arrive and look janky you can dispute it and will be protected.