Should I buy BTC on 6500, or wait to possibly go even lower?
You should get it now, don't wait till the price go lower because it ain't gonna happened. Bitcoin is fast rising and you don't want to miss the opportunity. And I just hope that you did buy it before when the price is below $6000 because by this time you have already looking at profit. However, if you didn't get you can still enter today at $6500 tomorrow we may see the price even higher and you will regret your decision not to buy today.