Amazon.com has some pretty good deals on parallel jaw clamps:
12" Bessey k-bodies for $20.99
http://www.amazon.com/Bessey-K3-512-...4?ie=UTF8&s=hi
or http://tinyurl.com/yl7o56

and 24" Gross Stabil for $23.23
http://www.amazon.com/exec/obidos/tg...X0DER&v=glance
or http://tinyurl.com/ybgpfs

Haven't tried the Gross Stabil clamps, but I've heard good things. And
$21 still seems steep for a 12" clamp, but I use my 6" and 12"
Uniklamps enough that I've often wished for a heavier duty version of
that.
Speaking of which, when I checked amazon to remember what the gray
baby-k-bodies were called, I noticed that set is on sale too: 2 @ 6", 2
@ 12", 2 @ 18" for $69.97. However, they're "in stock soon", which,
from what I've heard, means they might or might not be in stock
sometime this year.
http://www.amazon.com/Bessey-UNIK-6S...4?ie=UTF8&s=hi
or http://tinyurl.com/yeylp2
Of course they're not equivalent to real k-bodies, but as I said, I
have this set and use them quite a bit. I usually find them handier
than regular cheap F-clamps, with a larger clamping surface that
doesn't spin when you tighten it.
No affiliation etc., I just know I've been appreciative of clamp sale
postings here in the past, so I thought I'd pass this along.
Andy