If your HS trainer can hook you up, thats the best option. It's the same stuff, but free.
It looks like a resistance band...and a somewhat expensive one at that. I'll bet that if you go to a place like Target, you could find a set of three bands for that price.
I did just that about 2 months ago. 3 bands, two handles, and a strap (for ankles but works really well for closing in a door to anchor the band) for ~ $20.
You can also buy the resistance band material on the internet. I think it's called TheraBand or something like that.