That seems to be a little higher than the going price for name brand bikes from that era with full 600 componentry. I think I saw an Italian framed 600 equipped bike go on ebay recently for $300... Of course some of that depends on your location as well... and the specific model. With Columbus tubing, you are probably getting a nice frame.

My 1988 Centurion with full 600 and Tange tubes cost $115 a couple of months ago on eBay (I was expecting it to go for a little higher).

I think you would be happy with the Bianchi, if it is in good shape and is your size. Also if it is in good shape, it is obviously better than any new bike you can buy for $350...