You can get Home Alone: The Complete Collection on DVD for $9.99 from Amazon. This set of 4 movies is 67% off the list price of $29.98. It ships free with super saver shipping or Amazon Prime. Prices on Amazon can fluctuate, so be sure to verify the price before buying.
Best Buy also has the Home Alone: The Complete Collection for $9.99 as one of their deals fo the day. It's available at this price today only.