How to set up a site-wide Buy One Get One for $50 offer?

[AlexPAD]

I'm trying to run a SITEWIDE offer that is Buy One Get One for $50 where it takes the cheaper item and sets the price of the cheaper item to $50.

Is there a good app that will let me run this? 

[KabirDev]

For your specific promotion of "Buy One Get One for $50," where the cheaper item is set to $50, you can explore Shopify apps like "Automatic Discount & Gift" or "Discounted Upsells - BOGO & More."

Or you could have developed a quick custom solution for this particular need.