I'm using Envi-Blocks, found at
http://www.enviblocks.com/. I believe they are manufactured in Pennsylvania.
They now make two sizes: The 'original' size and the new 'Envi 8' size. I would suggest you take a good look at the dimensions of the interior of your wood stove's firebox before you decided which of these to order. I bought the 'original' size, which is roughly 10"x4"x4". As it turns out, this is just a little too big for my Hearthstone Morgan, which is only about 18" across, although I am continuing to experiment to see if loading them N-S instead of E-W will result in equivalent performance. (In fact, the Envi 8, at roughly 9"x3"x3" is probably just slightly bit too big, also.)
Anyway, if you go to their Web site noted above, you can send them an e-mail and ask them where some local distributors are. I found a distributor about 30 miles away from my house; since I bought and paid for them in May, I got a very good price per ton. With a pallet - which measures just under a ton - you get 315 individual blocks. The manufacturer claims that, in terms of total BTU content, that a ton of bricks is roughly equivalent to one cord of seasoned hardwood.
My best result so far, from a 'hot fire' perpsective has been burning them in a 'mixed' load - one or two small- to medium-sized splits, and two Envi Blocks. It burns really, really well.
From a 'burn time' perspective, I can pack in 3 or 4 blocks over a bed of hot coals (no splits, just the bricks), and once they get a good burn to them, I close off primary air almost completely, and I will get probably 5 1/2 - 6 1/2 hours before I see stove temp just beginning to taper off and I'll feel the need to reload.
I would expect that you will find a pallet anywhere from the very upper $200's to maybe nearly $400 at this time of year. If you order (and pay for) them in the spring, you might be able to get them in the $225-$260 range.
On the positive side, I find that they are a heck of a lot easier to stack and store than cordwood. Clean, no bugs, no dirt, no bark chips. Since they are
very low moisture, if you burn them right, creosote buildup should be quite minimal. Also, because of the low moisture and because they are really just sawdust, there is a surprisingly small amount of ash left over. I've got two tons (of bricks, not ash!) stacked inside my garage, and it gives it, interestingly enough, a pleasant sawdust odor in there. Also, on the positive side, when burning multiple bricks packed in tightly, you can achieve a pretty decent burn time before reloading, after a little experimentation.
On the negative side, they are more expensive than seasoned hardwood (assuming you are purchasing cut/split/dried cordwood from someone else, and not doing the work yourself). As for achieving a really nice high temp fire (i.e., above 500 F), you can do it, but at what I have found to be a pretty severe penalty re: burn time. So, especially from this 'burn temp' perspective, their performance, so far (but again, I'm new to burning these) is slightly less than good seasoned hardwood.
So there are definitely some trade-offs to consider. I would say that, given my (admittedly, somewhat limited) experience so far, that when you can get a ton of bricks for under $275, it's certainly a very worthy comparison whether or not to buy the bricks (but keep some cordwood - maybe a so-called "face cord" handy). In the high $200's to low $300's per pallet, then it's a judgment call, keeping in mind the positives and negatives I listed above. Anything over about $325 or so per pallet, I would
probably go with cut/split/dried cordwood.
