I got a set of 3 (two of which hadn't even been opened) on eBay just a week or so ago for $15.94, including shipping. Broadway Blast Off, Broadway Sweat, and Tone Up on Broadway. I think there were quite a few of them up for bid, so you might want to check eBay, if you don't mind VHS.
edited to add: I just reread your post, and see you don't use eBay... I'll try and preview these in the next week, and if they're not for me, I'll put them on the exchange, and considering what I paid for them, I won't ask much in return
I got a bunch of workouts lately - 32 in one trade! plus, I'd ordered a few (well, more than a FEW) so I've got a lot to do - but I'll try and look at his in the next few days.