Hello,
Yes, there are no tools that meet all your requirements. What I can do it, setup a tool that already exist and develop other tool on side that does what original tool can't do.
This is because if you want completely sync eBay-Amazon tool and order management tool, it will cost $1500+. But If you use already exisitng tool, and I design a extra tool to meet your other requirements, that would cost you less.
Thanks
Sam