2003 Ford Taurus Question: automatic transmission won't engage; acts like its in neutral when it's in gear.

My 2003 Ford Taurus suddenly wouldn't engage the automatic transmission and acted like it was in neutral when I put it in gear (reverse or forward). I had it towed and it is currently in the shop. They first told me that I needed a complete rebuild. I balked at the price, over $2,000, and told them I would need to think about whether the car was worth it. The shop called back and said that they could replace with a used transmission for about $1100. Since then, I have had 3 people tell me that I need a torque converter and a front pump. 1) should I call the shop and ask about a torque converter and front pump? 2) what would I expect to pay for a torque converter and front pump? Thanks!