best zoom lens for $500 or less (18-70mm range)

[surfnvb7]

company my dad works for granted a $500 retirement gift for 1 item. the item can't be over $500.

are there any good zoom lenses in the 18-70mm range for that price?

he has a canon rebel xti.

 

[wkahwkah]

I say tamron 17-50mm 2.8 there is few bad copies so
might have to return once or twice before getting
good copy but IQ on that lens is amazing... however,
no IS or good AF motor like Canon 17-55 2.8.
Though for 400bucks, I think it's really decent lens