Terry, I agree and support my Deere dealer for everything from replacement parts (including the laundry list of parts I am currently buying from Deere to overhaul my Kawasaki engine), service items (oil, filters, blades) and even the occasional overpriced hat. I do this for all the reasons you stated, plus they are nice, local folks who support the local community.
BUT, like Bill says, the 160 degree thermostat that my tractor was designed to use is no longer available thru Deere. The government mandated replacement is a 180 degree item. I understand the 20 degree difference actually makes a difference on these older, carburated, units.
I also agree with the comment about the suspect quality of cheapo parts. I will have to withhold judgement until I receive the 160 degree thermostat. I was surprised that a 160 degree thermostat, that will fit into this housing, was so hard to find. NAPA usually comes thru for me on things like this.
I will let you know how this thermostat works out.