Besides the belt and the water pump you should also change out all the oil seals and the oil pump o-ring (part of the $5.10 Fel-Pro crank seal set).
As far as the water pump goes, if you're going back in again I'd spend the extra $30 or so on the pump. If you can do your own work and don't mind going back in if it doesn't last another 5-years/60K miles, then no problem in leaving it this time. Many pumps last a lot longer than 5yr/60K, but I just change them (along with oil seals and pulleys) while in there, it's the time saved, as you have found out.
The pump shaft seal or the o-ring are know to leak. If the pump shaft has a groove worn into it that's another $30 or so. See the pump o-ring picture:
http://www.rockauto.com/catalog/moreinfo.php?pk=128254
A complete timing belt job parts list, prices on rockauto.com:
GATES K030295 Micro-V AT Power Steering Belt $5.14
GATES K050435 Micro-V AT Alt/AC Belt $14.10
FEL-PRO TCS45920 Crankshaft Front Seal Set $5.10
FEL-PRO TCS45641 Camshaft Front Seal $3.66
NATIONAL 221820 Polyacrylate Oil Pump Shaft Seal $2.86
GATES TCK199 (1 Belt, 1 Tensioner, 1 Idler) Timing Belt Component Kit
$52.89
STANT 48278 180° w/Jiggle Pin OE Type Thermostat $10.94
AISIN WPT010A Water pump w/o housing $30.79
FEL-PRO VS50304R1 Valve Cover Gasket Set w/Spark plug tube seals
$18.26
Subtotal $143.74
Shipping about $20