Buying a power cord from France, import duty and taxes?

Your hassle potential will be reduced if the PC is shipped via French Post>USPS as opposed to FedEx or UPS although I've had no problems with DHL.

There shouldn't be any problem. I received a 75lb integrated amp just a few weeks ago from Italy, and everything went smoothly.

And if I go through Paypal, then I should be protected if anything goes wrong, right?

Assuming you use a credit card (CC), yes, the CC bank will protect you. PayPal themselves offer little to no help other than the ability to use a CC.

Yes, the ad shows 15 Amp IEC US AC Plug. Is that what's being used in France? I believe France uses 220-240 volt, so does that mean they use a different plug?

France uses Schuko male plugs for their 230 V requirements. Google it to see what it looks like.
It is important to make sure that the cord not only has a 15/20 A IEC female connector, but that it has US male plugs, and not the Schuko male plug.

I only buy in USA why would you want to get a cord from France??

do it its fine I live in Canada and have never had issues shipping anywhere in the world. shipping is not that expensive as some here would say. I've bought and sold many items to / from the USA, Netherlands, UK,  etc. and never had an issue. one member said it depends on shipping method I've always used a reputable international shipping company or preferably the countries postal service as they will hand off to your US postal service in the end. Always insure and claim full costs better to pay the duties if applicable then get hosed if it gets lost.