Plain or plumbing pipe?

I investigated my bed project a little more, and I discovered there are two methods for assembling an industrial pipe bed frame.

One method is to use plain pipe and fittings.  In this method, the fittings are glorified clamps, so the bed gets clamped together using Allen wrenches instead of needing plumbing wrenches.  Also, pipes can be cut to the length needed rather than needing to figure out the number of pieces to get a 53-inch length of plumbing.  This results in a sturdier frame overall.  On reading through the Instructable for this style of bed, the frame is partially welded, so that defeats my purpose of making something that could disassemble and be carried in my Saturn Ion.

This is another style of pipe bed that uses couplers.  This one builds a wooden pallet, so it also is not the design I am looking for.

This picture, which does not provide detailed instructions, shows how to use this system to create a hanging support system.  It also mentions that this simple pipe frame cost the maker $500-$600 dollars.  Is that really what this project might end up costing?

However, these three designs do demonstrate that the plain pipe and clamp fitting method is viable.  In fact, I now have several sources for getting these couplings: McMaster-Carr, Grainger, and Hollaender.

The other method is to use threaded plumbing pipes, as done in my initial inspiration and the subsequently discovered loft bed plans (pictured above).  While I should be able to acquire most of the items needed for this style of bed at the Home Depot or Lowe's, the pipe is much smaller.  Some plumbing pipe beds use ¾-inch pipe; others use 1-inch pipe.  The coupling beds mentioned previously use 1½-inch pipes.  Also, the design of this bed uses ratcheting straps to support the box spring.  I'm not sure I like that.

What it boils down to, then, is what size of pipe I want to use and when to use couplings instead of plumbing pipes.  In my mind right now, I am looking at making the loft bed frame but making the coupling mattress support.  Now, I need to find out if the Lowe's will cut and thread pipe for me.

The pictures on the page appear smaller than they are.  To see them larger, simply double click on the picture.  Also, I always welcome your constructive criticism.  Click on the Comment link below next to the icon of a pencil; it may say “No” or have a number in front of it.

References:
DenVogel. "Aluminum Pipe Bed." Instructables.com. Autodesk, Inc., n.d. Web. 3 June 2014.

ladyada. "Pipe Dream Bed." Instructables.com. Autodesk, Inc., n.d. http://www.instructables.com/id/Pipe-Dream-Bed/?ALLSTEPS. 3 June 2014.

magicmex43. "Aluminum Pipe Bed Frame." Instructables.com. Autodesk, Inc., n.d. Web. 3 June 2014.

nerdologist. "Pipe Loft Bed." Instructables.com. Autodesk, Inc., n.d. Web. 3 June 2014.

willparks. "A Soft Industrial Pipe Bed Frame." Instructables.com. Autodesk, Inc., n.d. Web. 3 June 2014.