Cost to be competitive?

You're probably better of not starting over. You won't be in the top of the arena for awhile but you can build and gear an arena viable team in a few months, less if you spend money. Since arena only uses one team it, is relatively easy to catch up. Just g12 the right team, farm some speed mods, get a few zetas on them and you have as much shot as the someone who played for 2 years and has a deeper roster. The current meta is ep sith so that's a good choice. You won't get traya for awhile but neither will many of us but ep sith can beat traya assuming similar gear and mods. Another option may be jedi. With the gmy rework they can win on offense but suffer on defense. But there are two knights of the old republic jedi coming soon. Depending on their kits that may be an option too. New marquee characters cost about $300 to star but depending on the kit they can be viable at 3 star. I'd wait until the kits are announced before spending on anything. It should be announced soon since the characters are likely coming around mid july for the 15th anniversary of kotor.