Sorry, just saw this this morning...
Glad you figured it out on your own though.
west marine right down the street from my house... good to know its a source.
Don't bet on it being a source. I've found them to be very similar to the Walmart cheap fabric bin; they don't always exist at every store. I found something there a while back (don't remember what) and somebody posted a day or so later that the West Marine by them did not stock it. But, yes I buy a lot of my rope/cord there. I can't believe I didn't think to check for the shockcord. I thought I'd be done with West Marine when I sold my last boat....WRONG!
I think i've finally figured how i'm going to go about making an underquilt using this spare sleeping bag. a shock corded undercover (walmart bargain bin) that the sleepingbag zips onto to avoid the stretch issues on the underside of the hammock. (and because i hate to sew directly to my brand new HH)
I just want to take a moment to vent about cheap gear. I bought another sleeping bag yesterday (it was camo and less than $15, it couldn't be helped) for my cheapo UQ experiments. It is the Target brand (Greatland) and I'm pretty sure I remember something about China on the tag. We can argue about the global economy and the politics involved until the sun explodes; doesn't matter.
What does matter is the quality of products we purchase. Last week I found an old Coleman sleeping bag at a Thrift Shop; it had to be 15 years old. It took me a couple of hours of tedious work to rip all the seams on the bag. The thread would rip-out a few inches at a time when I pulled the two pieces of fabric apart. Then I'd cut a few more stitches and repeat the process over and over. I was happy the old thread would give me a few inches at a time that I didn't have to rip with the tool. The nylon turned out to be no good, but the insulation is in great shape; albeit polka dotted.
Now, brand new bag went on the cutting floor last night. Total time to rip ALL seams; about 6 minutes! I'm a fairly smart fella when I want to be and I do pride myself on being a quick study, but that's crazy. The thread used on this new bag is JUNK. With about the same amount of force used to open a bag of potato chips I was able to just pull the shell and liner apart. I think I cut about 12 stitches, that's it. I never used the ripping tool on the zipper. Just one long pull and the thing was completely removed from the bag. The insulation was useless; it looked like the insulation they blow into attics.
I'm just saying there is a HUGE difference in quality and all you have to do to find out is take one apart. I like cheap, but there is NO WAY I'd rely on anything made by this outfit; even for car camping. You're better off with a quality piece of gear made two decades ago than the useless piece of garbage that this company sells as a sleeping bag. Just a heads-up.
If your looking for shock cord, go to Harbor Freight. Look for there bungee cargo nets for pick-up trucks. Untie the knots and you will have tens of feet of it. Comes in two different diameters. Here is a link
Thanks unknown and welcome to the forum!