I haven't bought anything. I've unlocked quite a few things so I just used what ever experience and unlockables I had to boost myself up. Made a big difference already.
The booster packs are 240 microsoft points though and I have about that just sitting in my account that I, like Maca, have had sitting there for months. Not to mention that you have to play over 3 seasons in "Be a Pro" to unlock those damned things. Probably won't buy it still though because my guy actually has a wrister and can move now.