I think $6500 is the lowest price for BTC! Its value has gained a lot of recognition, and the number of BTC to be mined is limited!
How many coins are still available to mine? I'll probably buy more BTC to hold once there is 10% left. $6.5k value is still high at this current rate, let's just hope that its market value still goes down or at a perfect range in order to gain a good amount of profit thru holding. With the mining difficulty keeps going higher, we are still long way to go from what we are expecting. Let's also consider the coins that are circulating in the market, there are those who were moving and others are probably stored (holding). Still, there are a lot of parameters to hit my or each investors target, if this won't happen, I'll probably looking to hold coins (replacement to BTC) which has the similar potential of Bitcoin.
Still more than 4 millions BTC to be mined. 10% means 2,1 millions, so you are getting close enough to your plan. If you think that it will get lower price than what we have now when it is 10% remaining, then I guess you'll see the opposite price. It can be higher than what we have now when there are less btcs to be mined. You can start buying small amount of btc and holding it. We will not know whether it will get lower price again or not, so as long as you are ready to buy then just buy it.