Correct lenses for my Nikon D3100?

I have a Nikon d3100 and I want to purchase some new lenses. I'm considering buying off of Craigslist. Definitely, I will check for scratches and such, but my main concern is making sure I'm getting the appropriate lens for my camera. I'm currently looking at a NIKON AF NIKKOR 70-210mm 1:4-5.6, and a Nikon AF Nikkor 28-85mm 3.5-4.5. I currently have the stock 18-55. Are these lenses different enough from what I have to benefit me? Are these lenses correct for my camera?

The 70-210 is different, the other over laps what you have and is not going to make that big a difference. I sell all of my used gear on Ebay and I give the person 3 days to get it checked or try it out. Be careful on Craigslist. Unfortunately there are many scammers there.

Yes they will fit your camera. But you ask 'will they benefit me' without saying what particular area you're interested in. When people buy new lenses they don't buy them just to have a new lens, they buy one that will be beneficial to the area they photograph such as landscape, portraiture, wildlife etc.

Telling us your field and why you are looking at those particular lenses will enable us to judge properly if they will benefit you.

These older Nikon lenses are optically ok, will fit your D3100 but they won't let you autofocus. Only Nikon AF-S and G-series lenses will autofocus on a D3100, which lacks the physical motor coupling used on older or high-end Nikon cameras. (see compatibilty chart link below)

Since you already have the 18-55 mm, you could complement it with Nikon's 55-200 mm f/4.0-5.6 G VR (link below), which in my experience, is a joy to work with if you want to travel light and still need a decent zoom range. And surprisingly budget-friendly as well.

Buying the 28-85 would be pointless since you already own an 18-55. And neither will autofocus on your camera. Save your pennies for a Nikon 55-200 VR.