Feed grinder prices have really took off the last few years. The reason is that there are very few new ones getting sold. So good used ones are hard to fine.
Just Thursday I was at a consignment sale. here are what some grinder mixers sold for.
NH 355 with scale sharp $13,000
NH 355 older but still nice $8,500
NH 353 clean but heavy use $3,500
Gehl 100 nice but no scale $7,500
Gehl 100 no loading auger $5,500
JD 400 super sharp $4,500
JD 700 rough but worked $2,500
So you can see the value of a good grinder mixer is much higher than just 4-5 years ago. So if the JD 400 is as clean as you say than the $3000 price is in the market. There just are not many "deals" on good usable grinders now.