FBA margins question

Hey guys, my buddy and I have been doing FBA for about two months now. These first 60 days have been entirely learning and understanding our best approach to selling on Amazon. We eventually decided to settle with wholesale FBA with some online and retail arbitrage.

I’ll keep this short. We have done around $10,000 in product purchasing for our first inventory, but with margins, FBA fees, and referral fees, but it looks like we might only be doing 15% return. A majority of our products have anywhere between a 40% and a 60% margin. We’ve done as much do diligence as possible to be able to get the best prices that we can, but we’re having a hard time trying to figure out how to increase our margins.

There’s only two options. Either get products at a cheaper price, or have Amazon take less fees out. My main questions are this. As you become a bigger seller, does Amazon eventually start taking less out of your cut? And secondly, does anyone here have any advice for finding large bulk wholesale suppliers that are truly wholesale? We want to be able to purchase pallets upon pallets to send to Amazon. Anyone here got tips? We know it’s possible and people are doing it. There’s just a lot of mixed information.

Thanks!