I moved your thread to here, as it wasn't in the right spot
Welcome to the forum... Just like buying a car, you can just about buy a complete car from a parts store, but the price would be much higher...
Prices on e-bay seem 'cheap" for parts right now, so makes it harder to say. but all of these parts you see, you still have to buy a magazine and a frame ($100 to $150 each), less for a magazine that is a repro, but still, those part prices add up.
Frame : $150
Receiver
and barrel $150-$200
misc parts : $150
Toggle
and breachblock $150-$200
magazine : $100
already the prices are a minimum of $600, it is about a wash and that is if you get lucky...
Ed