Sigma 70-300mm f4-5.6 DG APO (Nikon, motorized) for $209

If you are looking for an affordable zoom for the Nikon mount, who can also autofocus with the below-D90 Nikon DSLRs, then for around $209, with free shipping, you can get the Sigma 70-300mm f4-5.6 DG APO, for the Nikon mount, with the motor. This is a 35mmFF lens, so you can use it on SLRs and DSLRs alike. When mounted on APS-C/DX dSLRs, you will get the "equivalent" of roughly 100-450mm.