On amazon or craigslist sometimes an item is listed a reasonable amount below what everyone else is offering (usually due to financial desperation). An example is an item that normally goes for $150 might have someone sell it for $100, and it’ll be bought within a few hours. So you have the regular price on a used object, then you have rare instances where someone wants to sell an item ASAP so they list it below the regular selling price of a used item.
Is there a software program where you enter the description of the item you want, a maximum price, the website you want to purchase it from (half.com, amazon, craigslist, etc) and when something is listed at that price it sends you a text message or email so you can purchase it at the lower price?