The easiest and cheapest way is to buy with leverage, it is also the most recommended, if you remember at the beginning of 2018, there were many “Shorts” because at that time they were buying Bitcoins, they were with many purchases, but the price was going down, it is the cheapest way to buy, also in margin when you are leveraged in "Short" usually occurs faster than a "Long" leveraged that takes longer and therefore is more interest.