I need to find a place to buy quick release buckles constructed from
all metal. The product I'm thinking of looks like this
http://www.coastalpet.com/products/cable_tie_outs/Spectra1.jpg but
something similar is acceptable. These must fit ¾" or 1" webbing and
be medium to heavy duty. A wholesaler is preferred (with a minimum
order no more than $100), but retail is fine.

A good answer will include a website or phone number of a company from
which I can buy these buckles.

http://apfoister.proboards9.com/index.cgi?board=Belts&action=display&num=1084542254

indicated http://www.strapworks.com/metalsiderelease.html might be a place to go. 

google search: side release metal buckle -plastic -collar

Thank you! Excellent job!