If you are happy to buy second hand car parts for your vehicle then you may be able to save yourself a huge chunk of money compared to prices for the brand new equivalent.
There are risks involved when looking to buy a second hand car part and unless you buy a refurbished one or off a dealer you may find that you have no warranty or even guarantee that it is going to work. Not only do you have to consider the risk of it being faulty, but also ensuring it is the correct part and fitment for your vehicle. Many people will not take back second hand parts because you have purchased the wrong one, it may be that you are then stuck with it.
If you can, always get a mechanic to check over the part or to at least confirm it is the correct one before agreeing to any purchase. Ask the seller if you can have any sort of warranty as even if it is only 30 days, it may be enough to see any intermittent faults.