as a lot?
if you check out ebay...you will get all kinds of prices across the board...for one.
sometimes they may sell for a $100+
sometimes someone may have one for sale for 30-50 bucks...
or as auction starting much less...

It is debatable as to whether or not you will get a high asking price...
It depends on the available supply for them on ebay at the time...
as much as whether there are people who are hunting for a n810 at the time you are selling ...and willing to pay what you wish to get.

Also selling so many as a lot...
odds are it may take a while to find someone who wishes so many ...

Also...as a lot...to make it enticing to buy...you may have to lower the total price for the lot ...just to make it more appealing.

Selling individually ...
they would sell more rapidly...
you would get a fair price...
and you could undercut the lowest going price on ebay and sell them thus.
Or wait until few or no one has any for sale on ebay...wait for a lull ...
then sell them for what you would like.

If you wish to just make your money back ...and perhaps a little extra...
I would suggest you flog them here...
here is where folks come ...
and there are plenty who would consider one.
If I had none...and wanted one..
Just the device...no batt or charger or anything...
I would happily fork out $30 and shipping.
With charger, battery etc...$50 and shipping.
It is a decent price...without gouging...and enough lure to sell them ..
more than $50 a unit with batt and charger and shipping and I think many would hesitate to spend more.
5-7 years ago you could have asked $100 a unit...
Now ...until they become a rarity ..(and at which point there many other issues such as software that functions...etc...) ...I doubt they will command a high price....or that many would pay it.

That is my view though...having been around the block...
also...for myself...
I already have a few ...so I don't need extras.

I do suggest you keep at least one or two as back ups...
just in case...
and sell the remainder...
that also...is just my thoughts on the matter.