I am trying to find a good price for Water Nipple and found some on e-Bay and a lot of them are buy-it-now with free shipping, but they come in large quantities. Is it good to have extras or do they last a long while? Right now we are using a regular chick waterer and a rabbit bottle and the chicks have taken to the water bottle really quickly so I think for the move outside that nipples would be best. Also, which is better the screw in type or the push in type? All of the ones on e-Bay are screw in type.