which you are willing to pay ACTUAL MONEY to maintain
This is sociopathy.
Don't put words in anyone's mouths. I got mine for free (it's a long, silly story). And if I get another one, it'll be by trading the straight-up ludicrous amount of spare metal I've built up over the past year.
Honestly, I can't see how backpack expanders are going to make Valve much money, since anyone smart enough to hoard their extra drops so they can eventually trade for the stuff they want instead of paying for items is also going to be too smart to spend real money on the expanders either. By the time you've converted so many items into metal that you've run out of room for even that, you've got more than enough to trade for a backpack expander.
Lord only knows where all the backpack expanders people are willing to trade off come from in the first place, though. Probably best not to think about it too hard.