I’m not sure what rifle you want scoped, but here’s the most inexpensive Nikon with bullet drop comp for 223/5.56
https://www.opticsplanet.com/nikon-p-223-3-9x40-bdc-600-rifle-scope.html
at $150. Good basic scope.
Optiscplanet sells a lot of spotting scopes as does B&H.
A four inch objective lens is a bit hard to mount to a rifle and would make the rifle seriously top-heavy. Spotting scopes can be had half that size (1/4 the lens area), but the bigger ones are a lot brighter at the beginning and end of day. But the big ones get way too heavy for packing and day hikes. Here's a 95 mm Swarovski. You can get a fairly decent used car with high miles for the price of this scope!
Glad to see you posted a link to Optics Planet. Was going to do that myself.
Great place to buy optics. Great place to learn also.