$250 - $42 (propane adaptor) - $20 (bbs) - $10 (plunger/spring set) - $20 to 40 for shipping/time wasted = $158-138
Used is used...buyer beware. It's up to the buyer to discover as much about the wear and tear of a used item and that they are comfortable with the state/condition of the item(s). Great sellers will go out of their way to fully disclose anything not-mint/new...but it's painfully obvious that's not always the case with every trade/sale.
Now, if the guy said that it was mint and that there were zero issues with it...I'd walk away from it. Why give $0.01 to a guy like that in the first place?
Best of luck getting this sorted out.