Re: Need some advice.
To begin with, the gun is an import, made in the Philippines. The company technically still exists (the name is owned by Armscor), but effectively is out of business and no parts are available. It is unlikely that a magazine can be found. Plus you say "everything that is wrong with it" which does not sound like it is in very good condition.
So the rifle is not usable as a repeater without the magazine. If the gun were in near perfect condition, and had a magazine, $100 would probably have been a fair price, but as it is, the gun is worth what you can get for it.