My wife and I also live aboard, I made one plywood
hatch each for the different sized hatches I have and did the work in phases. You could make plywood
hatches for all of them and do it all in one shot but would mean living in a cave for as long as it took you to do the work. Regardless, I wouldn't let that be the deciding factor.
Besides the cost of flat-out replacement there is the finish issue I mentioned. Not sure about how the Vetus would fit but the newer Lewmars have a larger radius in the corners which means you will have a gap between the frame and the deck
that will need to be filled causing a gel coat matching issue as well as a bunch of glasswork, maybe you are planning on repainting your deck
Besides that, consider you also will have labor involved removing the existing deck frames. Depending on how they are bedded (3M 5200?) could require whole lot of work which can be avoided by simply repairing instead of replacing.
As far as material cost goes, I got my sheet of acrylic for $250 from a new sales guy who was eager to get new accounts. Here in the US you should be able to get decent Mexican product for $350 and I expect thanks to NAFTA that prices in Canada
should be about the same. After that it's your labor, what's that cost?
Maybe not a dockside project
but if you can find a garage or shed you don't need a big space or much skill to do the job right. New hatches aren't cheap
, nor is painting a deck and having to remove existing and install new. My money
is on repair and I'd give you every encouragement to go the route
because depending on how many hatches you could be talking a difference of thousands.