 
Digi-Key also sells Quad Line Receivers, parts DS1489AN (68cents) and DS1489N
(48cents).  A Quad Line Driver, part DS1488 (48cents), is also sold.  I guess
if you don't won't to supply +12V, the chips with the pump-up circuitry might
be worth the extra cost.  But 1488's and 1489's are available at your friendly
neighborhood RS, parts MC1488 (276-2520) for $1.29 and MC1489 (276-2521) for
$1.29.