I am not convinced on custom wetsuits, at least the supposedly superior Rubatex G-231N ones. I spent $1200 on two 5mm (shorty and full jumpsuit) custom wetsuits from Wetwear and discovered that my stock 7mm Xcel with a hooded vest was MUCH warmer on my Galapagos trip (59 to 75 degrees). The problem may have been with the stiffer Rubatex G-231 neoprene, and the fact that I got large zippers so that I can don and doff quickly. Apparently a mistake, as the zippers just bleed to much of the insulation properties.
A stock wetsuit from Xcel or Henderson will probably keep you warmer than any custom until it is compressed (say 50-100 dives), as it just sticks to your body better and does not allow water to pump in and out like a stiffer G. Maybe a 7mm custom would work, but don't get the long zippers if you get the Rubatex.
I will keep the Wetwear 5mm custom jumpsuit for my diving in Hawaii because it doesn't compress and it will likely last years, but it just is not warm enough for much colder than 74 degrees or so, even with a closed circuit rebreather. I will get a new Xcel for my next Galapagos or Northwestern Hawaiian Islands (Midway Atoll, etc) trip, but I am getting a crushed neoprene drysuit for anything colder than 65 degrees or so.