What's your ebay profit for the past year been? How far under water are you? How many parts have you sold?
In another thread, someone said that profit is made on the buy, not on the sell. This was 10,000% truth. When you're selling the same no-name chinese garbage as everyone else, whatever they're selling theirs for is the most you'll be able to sell yours for. Your sell price is set, and it's already a saturated market. That's why folks are saying impractical.
Your only option to make a profit on this stuff will be to figure out how to buy it for less. Eventually this might mean special pricing agreements with suppliers, but right now, that probably means you buy in bulk for a discount and sell individually for whatever the market set price is. You might have to bring in 500 air filter covers(or whatever) to get the individual pricing down to something that make sense to do, figure out the import and taxes yourself, and roll the dice on the item actually selling profitably vs. you just bought 500pcs of garbage.
If you can get a source for genuine Stihl parts and sell them at a reasonable price, online, without getting yourself or your source in trouble, then fantastic. Good luck with that.
Not trying to rain on your parade, I'm genuinely hoping you prove us wrong, and come back here and say "I told you so." We're not in the same area or industry, we're not competing for the same slice of pie. When you make a go of it and buy yourself your third Ferrari, it doesn't take anything out of my pocket; the only way it impacts me is I get to read a cool story of success on a forum.
For whatever it's worth, this is coming from someone whose day job for the last decade has been business to business sales. Moved a couple million bucks last year.