For me this is one of those kinds of items that are so time consuming to make it is not worth my while to justify the cost savings. I am fortunate to live a few blocks away from Costco, I have purchased 2-3 skellies over the past couple of years. I will do the same this year, and then I corpse a few. I find between work and family my time is better spent on DIY props that are more expensive than the say the price of a Costco/Walgreen's skelly.
I think it depends, really.
I've come to really not care for the wally skeletons, myself. They just fall apart too easy for me to do much with them as a skeleton or a corpse. Sure, I'm certain I can find some way of fortifying the things to be useful, and I've fought them for years now and will likely continue to, but I've no real interest in buying more.
The Pose and Stays (costco), I have several myself, but they are just pricey enough, I'm not going to use them in every random prop idea I need a ribcage or torso for, and you have to take care of the slightly flimsy spine on those.
Now, for $15, I can build my own skeleton in about 2 hours (used to take me longer, but practice and all) using the plaster wrap method. Often, for us, that IS family time as well, with several of us working on it.