Take a look at some of the offerings of Allegro MicroSystems
, particularly the A390x series. It's purpose-built for your application. I think the A3901
could turn out to be a good fit for you; unlike the L293D, it can make it down to the 3 volt output you require.
The downside to Allegro is that their parts can be hard to find in less than tape-and-reel quantities, and I suspect you don't want to buy a thousand pieces at a crack. Newark
, though, has - at time of posting - 793 pieces of the A3901 on the shelf for $0.937 each (quantity 1-24, Newark part number 87K3379). Less than a buck is not bad for two full H bridges.
Now for the bad news. These parts are only available in dinky surface-mount packages. Unless you have the dexterity of a microsurgeon (and tools to match), I would recommend an IC package adapter
(you want the E11-0090 down toward the bottom of the page). It's not ideal: the pad on the bottom of the IC package should really tie to a large copper area for heat dissipation, but I don't see you dissipating more that 140mW in this part with two motors on (assuming you don't exceed 150mA/motor) which ought to keep its temperature rise below 30ºC. The adapter is $7.75 and for another $8.25 they'll solder your part onto the adapter for you, so for only 18x the price of the naked driver chip (or roughly $8.50/motor), you'll have something you can actually use.
"The age of the universe is 100 billion, if the units are dog years." - Sean Carroll