You have described what is called a "cash-secured put".
This is, in fact, a way of acquiring a stock that you have every intention of acquiring, except that you get a "discount".
Here's how it works.....
You like stock XYZ, which is presently at $45. You are prepared to buy the stock. You already have enough money in your account to buy it.
You look at the Put option for XYZ and notice that the December 45 Put is bid $0.50.
You can now sell the Puts ( 1 contract equals 100 shares ) for $0.50.
Now you wait.
If, on close of market Friday Dec 17th, the stock is going for anything more than $45, you simply pocket the $0.50, and repeat the strategy ( you may decide to change the strike price or the month fo expiry ). In this case, you have made a clean $0.50 times however many shares was involved in your transaction.
However, if the closing price on Dec 17th is $44.00, then you will be assigned the options and you have to buy the shares for $45 -- but you previously pocketed $0.50, so actually your effective price is $44.50. Viola! you have bought the stock at a discount.
The above is a very simplistic example, but it explains the concept. I have ignored commissions, in this example, but they can be significant and you have to consider their effect.
You could actually buy back the puts anytime before expiry, and have a capital loss or gain accordingly.
Note that you have to be approved for Level 4 options trading before you can sell naked ( or uncovered ) puts.
In another strategy, you could open a position by shorting the stock, then selling a "covered put". Then if the put is exercised, you simply buy the stock, and deliver against your short position and close out the trade that way. But I think this is more dangerous, because shorting a stock can be very expensive if the market turns against you ( margin calls, etc ).