Check with Frank Miller Lumber in Union City, IN. They regularly deliver to surrounding areas and I'm fairly sure Indy is on their regular route. Whether or not they carry anything that thick is another question.

The other way to go is to laminate up from 4/4 stock or make a mitered or lock-mitered post from 4/4 stock.

Here is a link that might be useful: FML

You will pay a premium for dimensioned hardwoods.

Try looking under 'hardwoods' in the yellow pages.

Below is one local dealer I use in norther Virginia.

Here is a link that might be useful: Colonial Hardwoods

I contacted FML and Colonial (hopefully will hear back soon) but brickeye, I think you are correct that even if I find it, it will be pricey.

I found this cool link which shows a technique for making a lock-mitered post: Stickley vs. Author's Technique but it is way beyond my woodworking ability!

This illustration BunkBed plans shows posts made by gluing thinner pieces together. I would need some help doing this, but it is at least closer to being in my range.

OTOH, the local lumberyard I contacted has 3 x 3 x 36 maple turning squares for $19 each.

The wood I am trying to match has a bit of whitewash, not sure whether I can get maple which matches closely enough? Will stop by the lumberyard today to compare.

Thanks for the suggestions!

Rather than trying to match the existing finish (which will be very challenging), you might use a contrasting color, or even paint, for the new parts.

BTW, lengthening bedposts by any significant distance without sacrificing structural integrity isn't the easiest thing to do. How do you intend to go about this?

Jon, the bunkbed is "stackable", meaning it's currently two beds, one stacked on the other, with a wooden pin/dowel in each post to connect them together. Like this:

Most loft specifications call for some sort of diagonal cross bracing, and we had also planned to have a desktop which would span the entire length. Sort of like this, but with the diagonal cross bracing:
{{!gwi}}
I hope this will make it stable enough, but I share your concern (especially since my son is rambunctious, and will likely grow into a fairly big teen :)

Our design isn't finished (just working from a picture, which I unfortunately don't have a digital copy of) So if you have any specific suggestions, feel free to share!

And that's a good point that we may end up painting everything if we can't match the stain (in which case the type of wood would be less important). I tend to be optimistic, though, and am still hopeful that we can get pretty close.

But now that I know it's not trivial to buy/make a 3x3 birch post, it probably makes more sense to pick up some small pieces and see whether it will even be possible to get a close enough match. So thanks for pointing that out!

"OTOH, the local lumberyard I contacted has 3 x 3 x 36 maple turning squares for $19 each."

That is more than $8 a board foot for maple.

Not exactly a bargain.

Brickeye, I'm new at this, but ...
I've seen maple for $3 ln/ft for a 2 x 4, so that would be $9 for 36 in. If I glued a couple of them together, that would be $18. (Granted, this would make a 4 x 4, rather than a 3 x 3)

Still, $19 didn't seem that bad. It is too short, anyway, so it doesn't matter (son's bed is about 12 in off the ground, so a 36 in post would make the underside of the loft 4 ft).

But I'm still curious if I am miscalculating? If so, how much should I expect it to cost?

I feel like I am fumbling around, but part of the reason I wanted to do this is for my son and I to learn something new! My father in law has actually built furniture before, so he will look over our plans before we start and be our "consultant" if necessary. Just trying to figure out as much of it as possible. : )

Birch runs $3-4 a board foot, hard maple around $3 and soft maple a little lower.

A local hardwood company would be a better source.
Wood is relatively heavy and shipping mounts quickly.

Your piece is not that large, but the size and weight limits on UPS show up quickly shipping wood.

I disagree with Brick on this one. If the maple blanks were long enough, they'd be a deal in terms of labor saving alone. It wouldn't make sense for a loft bed manufacturer to buy lumber at those prices, but it makes plenty of sense for you.

Kiln-dried hardwoods are only cheap when they're thin and roughsawn. It's very difficult (as you've noticed) to find thick chunks of kiln-dried hardwoods because there's not much demand for it, and because kiln-drying thick stock is much more time consuming (read:expensive) than drying thin stock.

If I went to my local cheapo Amish lumber dealer and bought 5/4 hard maple with the idea of machining to 1" thicknesses and gluing it together, I'd probably have to buy about four board feet per post at (currently) $2.79 a foot, or $11.16 per post for roughsawn lumber, and I'd have some work ahead of me before it looked anything like the turning blanks you mentioned. Besides time, that work would require the jointer and surface planer in my garage. (What, you don't have a jointer and planer...?)