Honestly, that'll be a hard sell. Using tokens, it'd cost <550 E to buy the recipe and orbs to upgrade a Sealed Sword to Avenger. Buying the Sealed Sword from the AH, probably looking at <1.5k E to buy everything necessary to DIY.

If you're intent on selling it I'd suggest upgrading it to a Divine Avenger, Punch rolling it, and hoping for something good. If you can get ASI or CTR on it, you'll have a much easier time selling it.