Generally speaking, having a scope on any gun dosen't add much value to the price. With a drilling it should because of the cost of the mounts if no other reason. But in looking through the drilling for sale adds it dose not seam to add a lot to the price.
There is a lot of junk out there that is advertised as rare and expensive thats not worth the price. Any gun collecting has a long learning curve. And then as DM says our expected use is a big part of the process of searching for the right gun.
It looks like a lot of drillings have older scopes that may or may not be serviceable for a persons use. I certianially would pay extra for a nice drilling that had a newer scope in properly fitted claw mounts. I would and did also pay extra for a regulated 22 insert as well.
Regards,