The problem with dorm style fridges is they leak when not hooked up to power and leak even more as the boat heels and the ice inside starts to melt.
The previous owner of my boat had one. He didn't care, and would let the water drain to the bildge, which, over the course of two years, ruined the cabin sole. I'm now trying to restore the sole, which is beautiful teak veiner, but without much success. I'm afraid I've have to replace the cabin sole completely.
So you will save on the dorm fridge now, but you may end up paying more later.
Yesterday, I ceremoniously took to dorm fridge out of my boat and will replace it with one that can drain properly. In the mean time, I got Coleman's camping fridge, it works with 12V, cigarette plug adapter, and most importantly does not leak. It costs under $80 at Walmart and will give me some time of good service before I get the "real" fridge."
BTW, Since this is my first post here, my name is Alex, I got my first boat 1979 Hunter 33 last August. I have been reading on this forum for a while now, and would like to say hi to everybody and thank all for great advice I always find here. I'm in St Pete, Florida.