You look at it, stupid.
A buyer should check the return policy of the store when buying used motorcycle parts. Used parts should come with some sort of guarantee for their performance.
There are used tractor parts that are worth buying. They will still have some use, but will all used merchandise buyer beware. Check out this site: http://www.countrytractorparts.com/
Anyone can find many used Jaguar cars using websites like eBay or Craigslist. The price range is lower than buying one from a dealer, because overall, the car is used (worth less). Prices depend on the model, but someone could find a bargain.
The disadvantages to buying used Subaru Imprezas are that buying parts can be expensive as they are usually only available at Subaru dealerships and they are not very economical on fuel.
I would recommend purchasing new parts to repair a broken backhoe. I recommend new parts because, although they may initially cost more, they will most likely last longer than used parts and, therefore, you will probably not have to purchase parts again shortly after buying them the first time.
who would buy used computers
You can purchase used and new GM performance parts on eBay. If you are concerned about buying from eBay, your local GM dealership would be more than happy to help you and even back order your parts, if needed.
Yamaha used and vintage motorcycle parts can be sold with Gogo Cycles. The "parts" market is more in selling parts than buying old, and used motorcycle parts. Try a salvage yard and see if they can purchase the Yamaha motorcycle parts.
How to check transmission and discover possible transmission problem when buying a used car.http://www.samarins.com/check/transmission.html
A Jaguar dealership will be the first place to start. One might try a junkyard but they are not likely to have many of these. Jag Bits is a good website and also, look on eBay.
No, I would not be interested in buying a used generator. I cannot think of why I would need one, since I live in a major city where outages are extremely rare.