Hi there Iced, and welcome to UCP. From waht I know (and I must confess I'm not a MB specialist) the 250S model W108/W109, was only produced between 65 and 72. The successor was the W116, wich was produced from 72 to 80.
It's a very nice car. And if there's not much wrong with it and you're into restoring and mantaining a classic car, that should be a trouble-free one. And the value of classic Mercedes is raising every day. To that you can had the argument that it is a car that allows you to make a trip in it, if you wish, with a level of comfort close to present cars.
It wouldn't be my choice as I tend to prefer classic sportscars, but I strongly encourage you to have your go into classics with that Mercedes if it is in as good condition as you say.
Good Luck for your business and we hope you enjoy UCP. We need more classic car enthusiasts!
Money can't buy you friends, but you do get a better class of enemy.