Where can I buy some coins with the cheapest price? Too many exchanger & trading sites out there, you don't know which is the best one.
The best way is to go to some meet ups with your friend or a trusted stranger and then buy it , buy it at the lowest value. That is called the p2p or the person to person trading , my friend do this and it help him and now he's sharing it to me.
At this day and age, which friend will even give you their coin at a cheaper value than what it is on an exchange unless they just want to help you in their own way? There are so many ways he can do P2P without even involving friends, that is, if the friend has the coins he is willing to buy anyway.
The best means is to go through exchange unless you are sure the source you are buying from is available to give you what you want, if you want to go the P2P way.
You are right. The P2P sometimes turn out to be even higher than the price on exchange because each one wants to be rich. Sometimes, in P2P, the seller tries to take advantage of the buyer when they know you are too desperate for a particular coin which maybe you cannot buy at a particular time on an exchange especially when the exchange jams up (happens normally with etherdelta).
One of the best exchanges to buy a coin is Binance. You can get many coins at cheaper prices.