Generic early-80s-ish Japanese gloss scope in near-mint condition. Nice.
I reckon you could get thirty to fifty quid for it. Which is a bargain compared to what that buys in new budget Chinese glass.
Ironically, you could get more if it wasn't an almost unknown brand. The identical item, from the same factory, but marked as Optima or Tasco, even Nikko Sterling or Original, would sell for more. Especially on E B ay, where sometimes silly prices are achieved for average stuff.
If I was you, I'd keep it and use it, carefully, on an old sproinger.