Building on what i said as well as soundguy. If you want to go the 2-4k$ route there are the old american gas tractors in 2wd. But in all honesty when you get to the 80s american tractors like JD or Ford or Massey, there all Japaneese tractors relabled to the american badges and specified changes but once the sheet metal is off there really no different than the Japaneese tractors that are the greys. Massey is Himonto or something right? JD is obviously yanmar, Ford is shirabus (which are they indian or Jap? dosent really matter i guess).
OK i got sidetracked. My point i was going to make. Besides the simple design of the engines and tractor in general ( i did not need 4wd or really want it, would be nice but did not want to pay) they sip fuel like i said, which in times of high fuel this is a plus. A friend of mine has an older JD gasser from the 60s. I think its like 37HP ish. He will use 10 gallons of fuel to my 4-5 gallons of deisel if were doing the same work. Yea he can pull a bigger plow but im talking running a finish mower or bushhog for a given area, we both can run a 6ft finish mower. Also the plus, for me at least is the weight. An older ford of similar HP from the 50s or 60s would weigh another 1000lbs+ as american tractors are set up to pull draft implements or ground engageing stuff, so they have mass. The japaneese tractors are designed to till so weight is not a big thing that is needed. Here is where this comes in handy. I live 3 hours from my farm. I tow the tractor between my residence or other places to help friends out sometimes. My tow vehicle is a 1980 1/2 ton chevy. That extra 1000lbs i would be towing around would really put a strain on the truck and put me over what i should be moving or easily moving it. I tow my tractor sometimes, disk harrow, 3-500lbs of extra ballast, the 2000lb tractor and sometimes a boxblad and the bush hog on the same load. This is all my truck wants. A heavier tractor would not be a bonus in this situation.
Also bigger american tractor can pull heavier implements which will cost you more. Im not talking 8-10 foot stuff but the difference between 4-5ft implements and 6-7foot implements.