Dropshipping has its advantages, but making a very healthy profit usually isn't one of them, especially on platforms like eBay and Amazon where you are up against some very stiff competition. That said, if you want to try dropshipping on the big platforms, then you might try a marketing stratgey like bundling.
As NP suggests, selling through your own site is always going to be the best option because you have less fees to consider and less competition. Of course it's not as easy as just setting up your own site, you need to have a very good plan to drive traffic because you can fill your own site up with great value products, but if you don't have the traffic, then you won't have the sales.
CWR Electronics: http://cwrelectronics.com
California International Sales: http://www.2cis.com/
Novatech Wholesale: http://www.novatechwholesale.com/