I think that most folks looking to get into an MC cart already have a MM phono stage so the only expense is the addition of a suitable SUT. An awful lot of MC carts can be handled with a 10:1 step up ratio.
Look at dover's experience with carts, he has had a lot of MC carts and they all fell into the 3 to 40 ohm range.
Something like the Denon AU-340 with Tamuri transformers has switch setting for either of those ranges. These transformers are very highly regarded and can be purchased quite reasonably from Japan.
So for the average person just wanting to upgrade into the MC league it doesn't have to be an expensive proposition if he already has a decent MM stage.
I started with my Audio Research SP8 preamp with phono and when I picked up my Denon DL-103 I started with the Denon AU-320 SUT. I was blown away with the great sound and later when I upgraded to the AU-340 SUT it got even better.
I don't have a great deal invested in my system compared to many, but it sounds very musical, more so than some expensive systems I have heard at other peoples houses or at dealers. I have yet to hear a system that I would trade for, maybe someday but for now it's a keeper.
BillWojo