If you are new to Just Answer, please read first: Once you have read the answer below, you will be prompted by the website to provide a positive rating (on your screen now, at the top, with the stars) for my efforts in answering your question. I hope that the information below will be of assistance to you!
Noble was a manufacturer and importer of Spanish SxS shotguns located in Haydenville, MA from 1953-1971.
They manufactured semi-auto, lever, and slide action rifles and slide action shotguns, in addition to importing Spanish SxS shotguns.
Shotgun models included the Model 420 (and variations), 420 EK, and 450 E. While most models were relatively inexpensive, good working, utilitarian guns, there has been little collectibility to date and most rifles are seen priced in the $75-$295 price range while the shotguns are priced in the $125-$350 range, depending on gauge and features.
Based upon your description of a shotgun in good condition, I would say that a value in the neighborhood of $250 to $300 would be fair.
Any other questions?