When I bought my machine about a year ago, I paid $26,500 for a 3520, 300CX w/60" HD bucket, and 447 BH w/12" bucket. I am not sure of the exact price breakout but I believe it was about $5800 for the 447 BH. I have been told that I got a very good deal so take that into consideration when comparing.
As far as choosing between the 447 or 448, I looked at that also and to me it seemed that the 448 was overkill for the 3000 Twenties. I'm sure that others would disagree with me but it just didn't look right. The 448 I thought looked to be oversized for these machines. That being said, I here they work fine together. But for what I do, I have never felt I needed more backhoe. The 447 does everything I ask and more. I have moved some very large boulders and am always impressed with what it can do with it. Which brings me to the point that always needs to be said... it depends on what you want to do with it. Maybe you could be more specific on your needs.
