I just grabbed some poncho liner's off ebay for relatively cheap (vs prices I see posted here) and thought I'd share the "secret".
I intended to buy 4 poncho liners. 2 to make under quilts with and 2 for top quilts for my GF and I.
I ended up getting 4 poncho liners for ~ $45 shipped. That's ~ $11.25 a PL.
Here's the secret: Don't look for "free shipping".
Many supplier's are selling PL's for $15-16 with free shipping, but if you look, there are other's offering PL's for $7-8 with $7-8 shipping. Seem comparable, right? Wrong! If you're buying more than 1, the shipping get's combined (and ebay calculates this automatically [just updated last week IIRC]).
For 2 PL's I think it ended up being ~$13 each. 4 for ~$11.25. 6 for ~ 10.50. etc.. I'm not sure where returns diminish, but if you need more than 1, definitely the way to save a few bucks.
I got mine from militarybase11. All four were in great shape, no tears/damage.
Be careful with some of the cheaper looking P.L. too, as many are advertised with damage.