Look around for the Reese version. The wife and I traveled to Canada after Xmas and stopped in at a Canadian Tire. They had an 8-ton capacity combo pintle-ball mount for $40 that was brand new, but an open box. Our M101 CDN tows great with it and makes very little noise.
I think that was for around 50% off, so normal price was probably $79.95. Look around and you should be able to find one for about $60 from many sources. Shipping weight could be an issue, though, for what kind of deal these may be.
I wonder if higher weight capacity pintle hitches are the issue? I know that the M101 lunette is probably the smallest size. If there are differences in pintles that are rated to tow bigger loads, maybe they are too loose when towing the smallest size lunnette?