Hey Zitt

It's a pretty major decision.
From experience, I can tell you keeping a printer like that running gets expensive.
You have to "feed" these things on a constant basis otherwise bad things happen. Things get dried out and nozzles get clogged... new heads can be from $1,700 to 3k alone. Plus you also need a technician to install it.

Printing with white ink is just asking for even more trouble. Especially if you are not going to use daily.
You basically have to clean the head every two days and the white ink is very expensive not to mention clogs lines and heads.
Varnish is very nice but also very expensive to use.

I know a few people who have Mutoh and they are happy with them. So not a bad choice but honestly ..dropping a lot of cash on a used one..hmmm I wouldn't..

Also the cost of vinyl is not cheap either. Have you ever done any kind of large format printing before?
You will need support..tech support at some point

You might be better off with something like this for your needs with a vinyl roll attachment added on.
https://epson.com/Support/Printers/Single-Function-Inkjet-Printers/Artisan-Series/Epson-Artisan-1430/s/SPT_C11CB53201

Just some things to think about.