Any ideas and advice would be greatly appreciated...
I'm no mast expert but fabricating one from timber has been done thousands of times over with a lot less stuff than is available today, so it seems a no-brainer to do it.
The rigging should be dead simple to fabricate too.
You'll need a compression post/ring frame/something under the mast to spread its load. Might be there already?
Comes down to what you expect from the rig and how much you want to spend... on my current figures I expect to get my rig completed for well less than $10K doing most of it myself, but it's definitely not a high tech rig.
PDW