I would suggest searching craigslist or other local sites for someone tearing down an established tank. Not only will you get much better quality but you will pay a LOT less and not have to pay shipping either.
Also, you can hand pick the pieces this way. I watched craigslist for about a month until I found mine for only $3.50 a pound and it was from a 3 year established tank.
I would never trust a site that offers free shipping as it obviously costs a lot to ship and they are getting their money some how... Also, if you must buy online I would like for someone that does pretty expedient shipping. You're going to get die off anyway. It all plans on if you plan on curing it yourself or not though.