Yes, definitely get yourself a decent humidifier insert ASAP. It will help stop further damage, & likely close the seams a little.
I don't like to diagnose a patient from a photo, but it looks like those splits have been around awhile, & in part might stem from hidden weaknesses in the wood (the mirror symmetry). The lighter-colored areas near the openings suggest that moisture has gotten in (whether condensation or sweat or cleaning liquids) and further dried out the wood. The darker stripes are probably some sort of contaminant liquid (hand oils or polish).
Though it does seem odd that the cracks run all the way to the butt, yet don't run out at all toward the soundhole.
Hopefully, it's never had a silicon "polish" used on it. If that damned stuff got onto bare wood, the contact area will be pretty much impossible to properly finish.
Though I've seen the Martin shop pull off some amazing restorations, I don't know this can ever again be 100% in looks. However, if the wood can be properly humidified, then maybe three cleats put in and the gaps properly filled and protected, that should restore most of the tone. Properly cared for, it could have another century of play in it. Still quite a pretty instrument.
Cost? Dunno; get quotes. Me, I'd rather cleat a top than try to repair edge separation. Stabilizing the cracks is MUCH easier than hiding them; up here, cleating & sealing would maybe be $200-$250 so long as you're more concerned with the sound than with making it look pretty.