It looks like the right piece to me, but I'm not an expert. How much is he asking?

yeah at the first glance it looks like genuine item! and he's asking 100 dollars shipped to my door!

That's not bad, sadly I don't know of a way to confirm if it's genuine. It's cheaper than brand new or and upgraded one so if you don't need anything more than stock I'd say go for it.

I did a search and came up with this...
https://stmtuned.com/collections/1g...sprocket/products/oem-mitsubishi-crank-pulley
The pulley in the link is just like the one you posted and it should fit ...

It's probably a genuine. Unlikely to be a knock-off. Some Chinese companies have copied even the label and the packing but MD376608 is a really old part number and many things were still made in Japan at that time, so around that era there were no knock-offs in the market. You can go if the price is important and if the glue is still working fine. But it's a very old NOS and it utilizes glue. If the budget allows you or if you don't want to take a risk, then maybe it's better/safer to go with a new from an official vendor or maybe a Fluidampr.

I bought one this past summer and it looked identical to that one but mine just came in a bag. Seller said it was oem

It looks identical to the stock pulley I have..I would ask for better pictures of where the rubber meets the pulley like said above it is a fairly old NOS and if it was me I would ? the integrity of the old adhesive and rubber. But it does look in good shape from what you can see. Just my .02¢, Jason Penny

I'm running a new, but parts store, balancer on mine and at 60.00 it is holding up. I DO keep an eye on it tho.