I live in Minnesota. Of the 7 months of the year that the lakes are not frozen, 4 of them are cold water paddling. All the downwind paddlers here have gone the wetsuit route. So you certainly can paddle the coldest conditions in wetsuits. Surfers riding storms on lake superior in the winter use wetsuits after all, an they spend most of the time just floating in the water.
High end super stretch neoprene is so much better than the old stuff. Some brands fit some bodies better in a kayak position. You really have to try before you buy, whether that is by going into a store or trying on online suits in your own home then sending them back if they aren't perfect.
It does require 2 or 3 wetsuits to cover all the whole temperature range. I have 4 of different thickness, so the cost of my wetsuit collection approaches that of a single drysuit.
There are pros and cons to each. Wetsuits are indeed cheaper, until you own 4 or 5 of them. Drysuits are less restrictive almost always. Wetsuits are nicer to swim in. Wetsuits still insulate if you get a rip in one whereas a hole in a dry suit can be a very dangerous situation.
There is one very important difference between dry and wetsuits that is very under-appreciated: The surface of a wetsuit stays wet in the air, while that of a dry suit does not. That means that a wetsuit suffers (or benefits I would argue) from evaporative cooling when in the air. Once in the water, the insulative properties of the two suits reverse. In the water, the insulating clothes and air spaces inside a dry suit compress, yielding a garment that insulates less well in the water than it does in air. The end result is that if you dress to be comfortable while paddling in drysuit, there is I think a slightly greater potential that you will be underdressed if you end up in the water. That is by no means a reason not to use a dry suit, but it is just something to be aware of.
Current Skis: Nelo Vanquish AIR, NK 670 double, NK exrcize, Carbonology Feather, Think Jet, Knysna Sonic X
Former Skis: Epic v10g3, Kai Waa Vega, Epic V12 g2, Epic V12 g1, Epic v10 double, Nelo 550 g2, Fenn Elite S, Custom Kayaks Synergy