HP35 RedDot on TOS

[HP-Collection]

On TOS you will find a HP35 RedDot for sale - a rare legend.
As an experienced collector I read the listing carefully and made notes:

- The computer was opened, so the back label is worthless.
- The serial number of the calculator is not readable.
- The mainboard of the computer was replaced by HP, no bug in the ROM.
- The optical condition of the calculator is ... let's say mediocre, but not bad. The RedDot is visible.
- As accessories, a leather case and a power supply is included, no manual and no hardcase.

But I was a little bit surprised when I looked at the price of the computer. I think $1600 is already too much.
I now have about a dozen RedDots in my collection, but except for one BIG Bug calculator I didn't pay more than $1200 for any of them (all unopened of course).
I would be interested in your expertise on this offer. What do you think and what do you think the calculator is worth?