I recently realized the lack of expressive anything I have for V4 and just my luck, i13's store goes on sale, but I'm a tad overwhelmed. I'm seeing things like RealBite, RealPucker, Boom Lip System, Expression Studio...

Does Boom Lip System make RealBite and RealPucker unnecessary? Does Expression Studio make them all unnecessary?

I could just get them all and be done with it, but I'd really like to avoid wasting money on any possible overlapping products.

One last thing, I use Perfect V4 Complete- does this make half of i13's Super Real unnecessary, or can they co-exist in the same figure peacefully (I realize it comes with 2 of the 4 products I'm confused over, which is why I decided to ask this in the same post)?

i13's Super real is a morph bundle of thel morph sets.

i13 Real Details, i13 Real Breast, i13 Real Smile, i13 Real Bite, Real Pucker, Real Belly, Real Rolls

Boom Lip System doesn't make RealBite or RealPucker uncessessary - they are different morph sets.  Studio expression is another set of facial morphs.  The Expression Studio is a collection of facial expressions, not morphs.

They all do different things.  I tend to mix and match these on my V4s.

All of these can co-exist with Perfect V4 - Perfect V4 is designed to fix flaws with the basic mesh.  i13 also has something similar - the OVERHAUL system.  I have both.  I have found it to be 6 of one, a half dozen of the other.  On the other hand i13 also did an M4 version of Overhaul, which I use extensively.

Thanks for the explanation. Time to start throwing stuff in my cart. :D