There's nothing quite as nice as a good Summicron on an M3, but one pays dearly for that experience these days. The collapsible model is still relatively inexpensive compared to the rigids and it can still deliver first rate image quality (IMO), but one can still expect to pay at least $450 for a good user grade model. The vintage rigid Summicrons are now selling for a significant fraction of the cost of very late model versions. Expect to pay the better part of a $1000 for a very good rigid today (sad, but true!).