Two years ago when I was in the market for convertible I thought I wanted a hardtop vert, so I drove the IS350c, the G37s and the 335 (of course I liked the BMW best). The sales guy pointed out that for a few thousand more I could get the six so I drove it and really liked it. Although it felt slightly heavier the active roll stabilization kept it so flat and planted in the corners, and I was hooked. In
Atlanta where I live the six was running about $7k more than the 335 of the same year (both CPO). So I started researching and eventually found a six two hours up the road that was only $2k more and bought it.
So my advice is to be patient and you should be able to find a six somewhere that isn't much more than the 335. best of luck.