I paid 25 for a brand new Shimano square tapered sealed bearing bottom bracket for my wife's Bottecchia Mixte at my LBS. I don't know if Shimano even does loose bearing bottom brackets anymore. It's probably nothing crazy so most likely a british threaded(common stuff). Just bring it down to any bike shop and they should hook you up or order something for you. They mostly run $25 plus or minus a few bucks on eBay or Nashbar/Performance or maybe even from your local shop.