Oh yeah, definitely worth it. You just pass the fees on to the customer so the only effect they have is on how many items are profitable to sell. Since I live in an area with a relatively low cost of living it don't take much effort to find stuff that is profitable.

Prior to starting to sell on Amazon I'd bought a grand total of two items from the site (both knives that are probably illegal in the UK) so I was completely amazed (and continue to be) when I discovered that you can mark up items several hundred percent and people will cheerfully buy them on Amazon.