Do you have pics that you can share? 5 years old and $1700 seems reasonable... but I’ll bet you can grab it for $1500. The two items you mention are optional... you wouldn’t need either right away. If your igniter works, maybe consider using it until it fails and then upgrade. And all 2 Stars come with the Flame Zone... you just won’t have the latest Funnel Flame Zone. If this will be your primary grill, then the Funnel Flame Zone is well worth the $$ IMO. But if you are gonna pay asking price and then add another $600 in upgraded parts, I’d suggest buying new and getting the bumper to bumper warranty that it would come with AND all of the latest and greatest components. I don’t think I’d pay more then $1500 for it. At $1500 I’d probably do it.
One thing you don’t mention is accessories. Does it come with any? That would change everything as MAK accessories are expensive and add up quickly.