I agree that this unit is a little pricy. However, in addition to knowledgeable value assessments, I appreciate that this site also offers advice and observations beyond market value. So, to add to Tom's comments, here are some additional considerations:
1) I do not believe the mower is an All Hydraulic (AHRM4H) model. It appears to be an early HRM48H.
Now, that should raise some red flags, since the AH tractors produce higher GPM oil flow than any other models and "special" all hydraulic implements were designed for them. Don't get too worked up, everything is not as it appears. While it is true that the AH models produce higher GPM flow rates, in practice you may find that the difference is not that significant.
For example, according to the Ingersoll Hydraulic System Specifications and Test Procedures Service Manual 9 99787 (version 7-97-RP-500-7), the -
4020 produces 7.25 GPM at 3000 RPM and 1500 PSI
4120 produces 8.25 GPM at 3000 RPM and 1500 PSI
The 4120 pump output is 1GPM (14%) higher.
Is this a deal breaker (assuming the price is right)? Not for me. If you used the mower deck with a 4020, you would probably run the engine at 3600 RPM to get the hydraulic flow needed to keep the blade tips spinning at an optimal speed. Hooked up to a 4120, just back off the throttle so you don't exceed the deck's operating parameters.
How can you tell the unit is an HRM48H? I have an early model. It uses two hoses. The early models used Barnes motors (two hoses-no case drain). Some later HRM48H (and early AHRM4H) models used Barnes motors with case drains. The last models used a different motor, but also had case drains. Unless I missed something, all AHRM4H mowers should have case drains.
Oh, yeah, you might also be surprised to know that the hydraulic motor is the same for the "regular" hydraulic mower and the "AH" mower. How did they do that? Well, the decks use a belt/pulley combination, and the HRM48H uses a 7" drive pulley and the AHRM4H uses a 6.4". The center deck drive spindle shows different part numbers for the two models, so those pulleys might be different too.
How do I know this stuff? Well, my motor had a minor leak. I took it apart to check it out, and when I put it back together, it had a major leak. I had to do some research. OEM hydraulic motors are expensive, and many of the motors are no longer supported. However, my hydraulic guy got mine fixed up and feels confident he can find a suitable replacement in the future.
2) Last point: The unit for sale is missing an important part (Cylinder Rod Mounting Adapter C33210), so add another $68.00 to the total.