That amount of shares is too low to create "ripples" in the market.
Usually you don't specify the price to sell the stock, unless you are personally on the floor trading the securities.
And even then, with a volume of $50,000 it would just mean you threw away $45,000.
For most people it would mean setting a $5 sell order, and the broker would understand that as "sell this security so long the price is above $5".
When you get to the trading volume required to influence the price, usually you are also bound by some regulations banning some moves.
One of them is the Pump and Dump, and even if you are suggesting the opposite, it might be in preparation of this scam.
Also, the software used for High Frequency Trading (what all the cool kids[a] in Wall Street are using these days) employ advanced (and proprietary) heuristics to analyze the market and make thousands of trades in a short interval of time.
On HTF's speed:
Decisions happen in milliseconds, and this could result in big market moves without reason.
So a human trader attempting to manipulate the market versus these HTF setups, would be like a kid in a tricile attempting to outrun the Flash (DC comics).
[a] Cool Kid: not really kids, more like suited up sharks. Money-eating sharks.