The D70 body seems to go around $400-$500 on eBay. The 18-70 is the kit lens, right? Those are going around $150-$200. Now, I think there's a VR version of the 70-300mm and a consumer version. I bought the consumer version new for about $120. I'd think they'd be around $75-$80 used. The VR version of the lens looks like it's going around $450-$500.
I do recommend this setup, though. I've got a D70s with both these lenses and a 50mm f/1.8 prime, also a consumer version. I absolutely love the setup. Consistently great photos and I've knocked off over 1,100 photos in a day *without* killing the battery.
Also, I believe you can install a free firmware update on the D70, which makes it into a D70s. I'd also recommend picking up one of Nikon's flashes (I use the SB-600) and I'm fond of the 50mm prime - it takes great shots and is fast.