any advice on where to buy parts to mod out my g37? i’d appreciate the input

 

...ebay...

 

try to shop local, save more money that way. For online retailers, you can get some upgrades at good prices at rockauto.
Then for performance upgrades, there are lots of online retailers that can even be found here on the forums. The list is huge, but just google g37 performance parts, sites like zpeed, stillen, conceptzperformance will have a lot of stuff.
If you really want to go for some of the best of the best stuff, look at administrationtuning for intakes. Lots of material on these forums, look around.