If I'm being completely, completely honest, there's a lot of "packs" which include many other items from the store, so his calculations are probably a bit higher than the reality.
HOWEVER. There's also a lot of special items you need to pay direct money for (like real life in-game band merch (yes, you could get Rolling Stones T-Shirts for your Sims)), and there's also items that are available for a limited time.
So, it probably works out to be either exactly the amount he said or even higher.