Dayton PT2C ~ $35 in bulk. I think you can get it closer to $30
if you call and place a larger order.

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=275-085&ctab=10

This is about $60 per foot, double the price of the small domes,
but there is less drama.