Personally, I’ve cracked anything between a 6 - 9 depending on the card and overall cost and condition. Checkout Show Off Your Last Cracked Slab (binder) thread.
The market for raw WOTC cards right now is pretty tough IMO. So many cards have been graded in the last few years that the listings for raw cards are often in very bad condition or completely destroyed in addition to being overpriced. Many times I’m able to find a 7 or 8 for the same price as raw but in significantly better condition. Additionally, as others have pointed out, buying a graded card can narrow down the potential variation in condition.