I would try and sell it for 150. I see systems like that in the store like that selling for 180, so I think you could pull off 150.
Taking into account the system has been RRoD, no controller, no HDD, and it being used. The system is worth at best 60 bucks. If I were the friend I'd rather go buy an xbox arcade.
I recommend selling it for half price of the lowest 360 package you can buy. That's pretty much 100 dollars seeing how you can get a 360 for 200 bucks now. You could go up to 125, but I wouldn't pay any higher. With the month of gold that's a good deal really. Too bad it had RRoD.
You can sell it for a lot on auction on eBay. Geeks like to disect broken machines. You could make around £100. Just give them the power cable if they ask for it. I sold my broken iPod for more than what I bought it for (I fell down the stairs with it in my pocket. Screen got punctured)