It also depends on if this is a dynasty league. If this is a dynasty league, I would keep RG 3 for the future. If it's just a one year and done league, I would definetly try for CJ. The person who would win in this deal for RG3 and CJ, RB, would be the person dealing RG3 for those 2 players.
Depends on how badly the other team needs a QB and the scoring system. I don't think CJ or RB isn't too much to ask. Both? That's a stretch, one that I would decline, but some people may be desperate. I would go after one or the other, then ask for a Tier 3 player to fill in for my bye weeks/injured players. Frankly, I would feel pretty good about picking up CJ only.