Welcome to the community, @Cary_Stein! Sorry to see that this has gone unanswered for so long.
The only way to have a record in one table affect a record in another table is to link the records together using a link field. However, that’s just the “how” of this scenario, and I’m more curious about the “why” that’s driving your request. Something tells me your data model might need a tweak. Are the SKU values the same in both tables? If so, I strongly suggest combining them into a single table, and using different fields to represent changes in price.
If there’s some reason that the data has to be in two tables, please explain. Linking would get the job done in that situation, but it would need to be done manually (even with some shortcut ideas I can think of). There’s no way to make automatic links between tables.