If you want to try to sell it, take a look at www.dotmed.com. It's an auction/sales site for used medical equipment. I'm not sure what's required to get an account to sell on there, but you might be able to refer your customer there or refer a broker from that site to your customer and ask the broker for a finder's fee. I'm not sure it will be worth much money though. The x-ray tube in x-ray machines need to be replaced occasionally and I'd guess that the machine did not have it's tube replaced anytime close to when it was removed from service, and they are not cheap. Also, with increasing media and government scrutiny of radiation doses from diagnostic radiology, most hospitals will look for a newer machine that can take quality images with reduced dose compared to machines from 10 years ago. If you're going to export it, there are a lot of hoops to jump through both in just getting the OK to ship it out of the US and then alot for getting it into another country (there requirements may not line up with the FDAs).
Before you get involved with this, do some searching on the FDA website, as well as your state governments' site. The FDA has a lot of regulations concerning the use of X-Ray machines, and you can get in a lot of trouble for misusing them. Also, while X-Ray machines don't have an actual radioactive source (they accelerate electrons into a tungsten, molybdenum, or rhodium target to create bremmstrahlung radiation that is then used to create the images) it is possible for the target to become slightly radioactive over time, and will be subject to specific regulations concerning sales, shipping or scrapping. If you set off the radiation alarm at your local scrap yard, they will not be happy with you.
If you've got an questions, let me know and I'll try to answer them or point you in the right direction. I'm just finishing up my MS in Medical Physics, so I've got some experience with the regulatory side of radioactive medical equipment.
Bob