Well, if it was working i'd say about 75 bucks max. Since it's broken, I wouldn't expect more that 30 bucks. I bought a water damaged ipod touch 4G to add to my collection and the highest bid (mine) was 29.50! God luck but don't get your hopes to high!
With it being a pre-production test model iPod touch, I think to the right buyer this may be worth a decent amount even if it is not in full working condition. Do you have any pictures that you can upload?