Here are a few links to coarse perlite , not sure how good the price is .
first link size #4 averages 1 inch
size # 3 averages 1/2 inch
http://www.horticulturesource.com/product_info.php?products_id=5934
next link has smaller size perlite average 1/16 to 5/8 average
http://www.norcalperlite.com/NorCal3.htm