Where are you located? It depends on where you are. Excluding costco, Amazon is your best bet, and if you want to cut down on shipping, wait until a holiday or sale. I'm surprised it's not prime shipping, when I bought my brick from them not too long ago it was prime and got it in 2 days.
You have to put in work, but when I first got started I hit up garage sales. You may not find a brand new brick... but I guarantee you'll find cards new and used very cheap.
Magicians/Cardists and collectors appear to be the only groups that know or appreciate the value these simple pieces of paper possess.
try your local magic shops or, as mentioned above, wait for sale if you're patient enough. I know T11 have done them for $1 per deck before in the past when they were getting rid of old stock.
Excluding costco and other whole sale stores? You can probably find them on Ebay for about $12.
Walmart is great.
Sometimes if you buy them from magic stores, including online ones, they can be very cheap.