Tamron does produce a 70-300mm version with built-in motor which will AF with your D60. Capable to produce decent images at 100-200mm. FYI, I got it much cheaper than the quote you got.
I would advise you to get the Nikon 55-200 VR, at the long end, VR does help alot if you are not using tripod. There are some good bargain in the B&S forum.
Cheers!
the 70-300 tamron doesnt have image stabiliser like VR?