Ad says $750. Depends on components really. If it's a full 105 grouppo and is in good condition run ivwould agree to it being worth it. If it's re base model, retail on a brand new one is $880, so you could probably get a new 08 or 09 for $800.

Even if he doesn't know much about it, he can look at the RD and tell you what model it says on it before you go check it out.