Those that I know that are selling on Amazon are doing great...highly successful.
What you need to strive for is to not be just a regular seller...but to move up the ladder to featured merchant and higher.
Those sellers receive more perks...your own rep who calls and moves you further along faster with Amazon.
The good thing about Amazon is search engine placement. VERY HIGH!
The store cost isn't that outrageous to try a month or two.