The moons in OP's image are out of focus - they're not that big compared to Jupiter.

Do yourself a favor and don't go wild spending money on new equipment; just wait for a calm, clear night. Jupiter and its moons are a bright object, so you don't need anything fancy to get a good view - a good eyepiece might make things a bit clearer, but filters (and especially fancy expensive ones) won't do much because your biggest enemy to a clear view is actually the atmosphere.