Would it be the end of the world if I use salted butter in place of unsalted butter and NOT add salt to the batter? I've read articles claiming that unsalted butter + salt would be better, but how much better is it? Is there really a huge gap of flavor between using salted butter vs unsalted butter? Good quality unsalted butter costs $5.44/200g (not even 225g!) in my country, and so I've never really tried using them...

I find salted butter too  salty to be used alone. If the recipe calls for MORE than a pinch of salt you could try a 1:2 mix.

Or use margarine instead of butter. 

There are also recipes which use oil...

I never use unsalted butter. No matter what the recipe says. I have never had any complaints about things being salty.

The salt in salted butter is very little, I use them interchangeably and no difference in cakes,cookies, or icings.

I've always used salted butter and have never had any complaints about my baked goods being salty.

 I only use salted butter when the recipe I have does not include salt. I also use salted butter in icing so that the icing will not be as sweet. Like someone said, I don't think there is a whole lot of salt in the salted butter to really make that big of a difference. 

I only us salted butter when the recipe calls for salt. I made a recipe that did not include salt one day and it was not very pleasant.