Make sure the batteries all charge properly before buying. Any Mavic Pro batteries will work bit are either gray or platinum color.
Absolutely vital to check all batteries and cell health.
If it's been sitting around, the batteries could have suffered health wise, even be doa.
A lot depends on if you can 'test drive' the drone, if you know, or how much you trust, the owner, trust their testing for you.
ALL M1P / MPP batteries are now getting very scarce, made obsolete by DJI, in the US you may still find some around with the market size and number of resellers.
But you can also get aftermarket Powerextra batteries that seem to get a decent review by others here on the forum.
Love my M1P and yes it's quite rare the alpine version, could be collectable in years to come, also great to fly still and enjoy.
BTW, that looks like a flymore package with the bag, 3 batts etc, but I can't see the 12v car charger ?
Might pay to ask if they have it, as they are very handy for car touring / field trips.