Is this fair? My friend wants to buy my cell. (long)

DH and I recently switched to Droid X phones and we're really happy with them.

My co-worker came to me today and offered me $50 for my old cell phone. He needs a new phone, but doesn't want to have to upgrade at this time. I have the LG VX8700, also known as the Prom Queen. Yes, really. I loved that phone.

I splurged a bit and bought the extended battery for the phone. The extended battery meant that, even with all the talking I do (and heavens I can talk!) and listening to music every day for at least an hour while I walked, I only had to charge it once every ten days or so. Bought a music package (earbuds, music disk for extra storage, the Verizon music CD -- which I don't think is even valid anymore -- and SanDisk for extra picture storage). I have all the stuff....manual, wall charger, the computer charger, even the original box. The phone is in excellent condition as I was always really careful with it. The way it is now, the poor thing is just sitting in my desk drawer.

Anyway, I told him that I didn't want to sell it, but I'd just give it to him. And really, I have no problem with that. He's married with two young children and his wife isn't working right now as she's a SAHM. He was shocked and says he has a problem taking it for nothing. I have a problem accepting money for a phone that -- although it worked beautifully for me for the four years I had it -- could develop a problem simply because it's four years old. And when I talked to DH about it, he has a problem just giving it away and thinks I should accept the money.

But if something happens to the phone, I have to work with this guy; he's in the cube right next to me. And I would feel horrible. My co-worker was checking the Prom Queen out on eBay and he told me that he'd end up paying more for the same phone there with no extended battery.....I remember that the better battery alone was $50.

I guess that I simply don't want to take advantage of somebody. And if somebody else can really use something I'm not using, then wouldn't it be a good thing to give it to them?

Am I being ridiculous? Am I being fair? What should I do? Any suggestions?

That's what we agreed on this morning....and it was his idea. He's thrilled to death with the phone. And he told me that if I didn't take the money, he would donate it to a charity of my choice. I picked the local SPCA and asked that he donate it for Mollipop. He started laughing and said he'd do that. So it worked!