Craigslist is best if listings are free in your area. No shipping, and no disappointed buyers with after-sale issues. Expect a couple of generic "is it still for sale" emails or texts; don't answer any of those.
Since you ask for other options than ebay, I guess you want to sell and ship internationally. As extradarcafe stated, this means packing the instrument safely. You also need to choose a courier that provides insurance for the instrument (package). I do not know where you live, but the latter can be a problem.
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