Prices are usually set at a point that the manufacturer feels the product will sell well, and hopefully be profitable. They don't use a formula. like, Cost+17.3%, or whatever. If Deere felt like they needed a competive boost, they can sell at less $$ than NH and Kub, with even better specs. (theoreticly, I am not suggesting that that is the case, here...)
Deere can also have changed there yardstick, changing how they establish these numbers. They have seemed to be very conservative in the past, and probably still have plenty of wiggle room...
Often times, a product has fantastic markup, since the higher price gives a perception of a better value.
I haven't checked, but I am pretty sure the 300 series is all the same frame, just different brackets and cylinders. That would be a real cost savings for Deere. It would really be cool if the dealer can order a base version and equip it to whatever version the customer wants...