Depends. I bought Stellaris, HOI4(including season pass) and EU4 at full price. When it comes to DLC, I'm more likely to pay full price, particularly if it's content I'm interested in. For instance, I haven't purchased the last 5 EU4 DLC(or country packs...whatever) because I'm just not all that interested in the content. I am more interested in I:R now than release but am holding out for a sale. However, I plan on buying the DLC associated with the EU 4 European update and the new HOI4 DLC at full price.
If they announce Vicky 3 at PDXcon I will more than likely pay full price for it...as long as they don't mess it up too bad.