I agree, not worth the price. They are $399 brand new, bonus that that one does not have the tool-less tensioner easy start. If you are really wanting a saw that size, maybe offer $100 and haggle up to $150. I guess it all depends on what you are wanting to use it for? Tree limbing, firewood cutting, chasing neighbor kids who are ding-dong ditching you??
This saw does claim to be a "wood boss", "The MS 251 WOOD BOSS® is perfect for felling small trees, pruning and thinning, and cutting firewood simply and efficiently." It will cut firewood, but I think they are thinking for camp fires, not necessarily cordage. It can be used for larger firewood cutting, but it will take you a lot longer than using a larger saw with more horsepower. - Again, it all depends on what you are wanting to use it for.
I don't think you will see an upgrade from your MS 250.