The Sally 4th one looked quite good, but I can't find it now either. Empires at War have a model, but I've no idea what it's like in person. I've got the GW kit in the lead pile and the bridge is 125mm from the ground if that's useful information, I see there is one on eBay finishing up tomorrow and currently at £50.
Personally I'd probably scratch build since I've yet to see a really nice kit and it's not a complicated build. I remember doing a couple when younger, not quite sure if I ever actually finished any of them however!