Perlite, cheaper, I have been led to believe it tends to float to the top of your mix??, and Mel, finds it unattractive??? not sure if that means it is no longer working?
I personally, love the principles behind Sq Foot Gardening, but find a lot of things he says are too evangelical on his method, for my taste.
I used Vermiculite as I live in an area which has a good rainfalls all year round and only rarely need to water, so I did not use a 1/3 mix, tops have a cupic foot per 4x4x 6inches, it worked for me but I have high rainfall.
the Vermiculite based on my small usage and the fact I seed start in the stuff, so over the years will increase in percentage, was affordable!! just, I did grit my teeth and inhale deeply when purchasing it!
if I was on a budget, in a dry place I know I would have gone for perlite, and maybe a couple of bags of vermiculite, and over the years added more vermiculite as I could afford.
You need to sit back and think on the water needs, and bank balance, perlite is fine by me, but I realised with the run for your life rain storms of CT, I needed something that would drain rather than something that would retain water, so I added a wee bit of sand to my mix as well.
I don't think either is better, you have to identify your needs and adjust accordingly, no point in starting a garden to save money if you break the bank in year one?
I have only proper gardened for a year, but that is my take on it, my water bill did not increase last summer due to the garden, but in a dry place I think you need a lot of either of them, good luck and keep digging :-)

Well, I've been gardening at my current house for 6 years and for years at my dad's house (growing up) before that. I started my simply digging in the existing soil, and planting traditional "beds". Next, I went to some bordered beds, and over the last two years started really expanding into the "Square foot" method, although I do not follow all of the instructions in the book.

In thinking of expanding new beds, and increasing the heights of existing beds, I started to think about the perlite/vermiculite dilemma. Vermiculite is hard for me to come by in large bags (a 90 minute drive out to Amish Country), and expensive on top of that. Even in Amish Country, a 4 cu ft bag is about $15. I am considering whether or not perlite would be as effective at keeping the soil "fluffy" and allow for proper drainage while still retaining water. Perlite is a standard ingredient in most potting soils, so I assume it should be fairly comparable.

Personally, I don't care what the soil itself looks like (attractiveness takes a backseat to function in my veggie garden, of course, this is not true in my wife's flower garden!). If things go the way I hope, the plants will fill in the bare spots quickly, and the soil will only be visible to the person working in the garden (me), but from a distance, the casual observer (wife) wouldn't be able to tell a difference.

O.K. eagles they are not the same you might spend some time reading up on there use and properties. vermiculite will hold water like a sponge internally, breaks apart/down rather easily and compresses under soil weight. perlite holds water on the out side drains easier and does not compress under normal use, it does float up to the top of a mix in a heavy rain. I would think either would work in a raised bed system. I only have one small bed with Mel's mix (vermiculite). Too spendy for me to enjoy. The rest of my beds are soil and compost,but I do Square foot garden and love it
Curt :-)

I think, and I am sure you are there on that, perite is what to do, I remember when I found out how much vermiculite was in my area, when I finally found it! I paid $26.99 before tax! for 4 cubic foot! I too, don't care what my soil looks like and given what curt grow said, I am really thinking it is better, but I have the twin devil on my shoulder in DH who was a scientist and a plant biologist to boot, who said he only ever used Vermiculite? but is vague on the WHY? this was in Scotland not US, before I moved here I had never heard of the stuff, perlite is in all UK mixes as well.

I noticed the potting soil I bought to go in the bed recently had perlite in it. We cannot find vermiculite here where I am at and I was not going to order it and pay the hefty price. Even that was pretty costly and I have been thinking of a cheaper way to go about the whole soil thing. I am thinking of just top soil from a bag, and compost...call it a day, add some side dressing if I think the plants need it.

Perlite loosens the soill but will NOT hold water like vermiculite. I water retention is critical try using used baby diapers. (Not eh kind with poopin them only thos e peed in. Break them up in pieces and add them to the soil. they will retain moisture and the urine contains Nitrigen which aids in the groth of greenery