I too played with the idea of creating my own figures, but at this point in time I don't have the confidence in my abilities to carry it through (perhaps a little further down the track). I do a fair bit of searching around looking for a particular figure to incorporate into a scene. For example I found some really old Tamiya stock in a local store. Though the kit had four figures in it, I was only interested in one of them. The cost of the kit was minimal and I got the figure I was after. These figures were all pretty basic in comparison to the Tamiya standards of today, but after taking to it with my trusted hobby tools and then adding some more detailed accessories I achieved a really good effect. What was once a fairly ordinary figure now appears to be one of your more up market pieces.
While this does not fully address your desire to sculpt your own you can derive variations on your figures a alleviate some of your concerns with concept of seeing the same figures appearing all over in dioramas.
