Don't write off a good used tiller either. I got a 1976 Troy-Bilt Horse that is a real rugged workhorse. I got mine for $50 becuase it had a blown engine. I spent $230 on a brand new Briggs and Stratton engine and now I have a great machine that will till circles around anything new under $2,000. It doesn't look pretty but it's a beast and replacing the engine was a piece of cake and took about 30 minutes start to finish. I just had to make sure the bolt holes and shaft were right but it is a very common size and there were about 20 motors that would have worked. Harbor Freight carries their Chinese ones that go on sale for $99 several times a year.
There are also lots of good old tillers out there that don't need repair. They are almost like exercise equipment, people buy them then find out it's harder work than they think so they collect dust for years until they get sick of tripping over them and sell them cheap.
Also, if you have the time you can offset the cost by doing a few local tilling jobs. I did that and it paid for itself in one season. I had one big tilling job 5 minutes from me that I got $200 for 4 hours of tilling. Just some food fgor thought, best of luck and don't forget to check back to let us know how you make out (pics are appreciated :smile

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P.S. Mac, those are great looking machines, what brand are those?