Upgrade or buy?

Hey everyone! I have a OG MK3 (Maybe MK3S can't remember while I'm at work posting this) and was wondering if it worth spending the money to upgrade to the MK3S+/3.5/3.9/4 so I can use the MMU 3 or just buy a MK4 and MMU3?

Is it worth the work to upgrade my current printer and save maybe like 300/500 bucks or just get a second one and find room for it haha