You're facing three major issues with this business model you are trying to implement.
Firstly, you're not actually trying to purchase from a wholesaler. A Sony reseller is a retailer, they're not a wholesaler. As you have correctly identified, Sony has a network of resellers who they retail products through.
Issue number two, purchasing in such low quantity form any retailer will not get you much of a volume discount, if any at all. Thirdly, these types of products have very small margins to start with, and don't need a high margin because the reseller's make their money on turnover.
So as you can see, there is very little opportunity that exists by exploring this avenue of supply, hence why you are experiencing such problems.