Are you on a budget? If so and if I was you, I'd just get some barends on there and pretend I was running bullhorns. Assuming you wanted bullhorns in the first place. You can probably get takeoff barends for a couple bucks or maybe free if you're near a good bike shop.

Of course I probably wouldn't even convert that bike unless the rear derailer or rear wheel was totally busted. I'd just get new cable/housing, lube stuff up and roll out. If the shifting still sucks after that put the shifter in friction mode. If it still sucks after that just slide it in so you never touch it then it's just like a single speed

But to answer your question, are they like new? If so I reckon $20-25 for the bars if that was the shape I was after. Maybe $10 for unidentified model stem.