I have a new D70 with the 18-70mm kit lens and also a 50mm 1.8. I imagine that
once in a while I'll want to do some deeper shots. I see the Sigman 70-300mm
APO is a popular low cost choice for under 200.00. Is there anything else I
should be looking at? A 70-200mm would also work. I'd rather not spend more
than 400.00 or so. It seems that after a lens like the Sigma there is a HUGE
price jump to the next level. Anything in between?

Thanks for any tips on the most played out question ever!

RB