I have a Romba spear living amongst the crevices of one of my sofa's. I accidently dropped it down there a couple of weeks back. Alas it hasn't resurfaced yet, but if it does, then its all yours, because Romba has gone now lol
Can't help with the other items, though I see a lot of coins getting traded on RS quite often.
The Warok bow on its own won't be cheap, It might actually be more cost effective to buy a complete Warok, then sell off your incomplete one.