Sorry to hear this PL.. yeah, with an interference engine it means when the timing belt breaks, the valves stop in one position and the pistons on the crank keep turning and kiss the valves. Id asked this and thought you had a noninterference engine when you said your mechanic told you timing belt and water pump... Thats too bad.
Michel.. for junkyard stuff to fix this you have to get a complete engine. Either that or buy new pistons, conrods, valves and get teh heads and block redone then rebuild the engine. Not worth it. It might be worth to find a used engine.. but then again probably not. Labour like you said is what kills things like that.