Buying old electronics is not recommended because every electronic has its own age after which the electronics shouldn’t be used. This is how the theory works, the electronics generates the heat and after generating enough heat which happens running electronics equipment’s a long time about a year or more years the circuits and capacitors and other parts of the electronic equipment tends to fail which is why it is not a good idea to buy old electronics.
This doesn’t mean that you should not buy old equipment at all, the above paragraph was to let you know the actual view behind not buying old equipment. There is one more scenario which you can follow if the electronics are new and under warranty and someone is selling it then it is a good idea to buy because that equipment hasn’t generated the heat year which is why you can use it for another one two or more years.
Most electronics comes with a 1 to 5 years of warranty only few comes with a lifetime or 10 years warranty which makes them an equipment can work a few more years after the warranty expires. The whole scenario depends on how the electronic equipment kept and maintained, if the condition of the electronic equipment is very good like new then you can consider it buying immediately only after few tests which are necessary because there could be manufacturer defects.
Learning about buying is ok but where to buy is another question which can be bought on free classifieds because these days all old electronics are being sold online on classifieds. Classified website is the only platform on the internet where old goods are being sold and there are literally millions of buyers who are interested in buying old stuff online without any hesitation.