My suggestion to all new builders is to locate the proper materials first before they build. You might be proud of the uke you made from your grandmothers old pie cabinet but look at all the time and trouble it takes to get it to a workable state. You are going to be spending anywhere between 10 and 100 hours on this project no matter what kind of material you use. Why not start on the right foot. Having the right materials will be easier to work with and the finished result much more rewarding, and then you are more likely to build another, and another and so on.
Not necessarily Chuck. There is a real satisfaction to be had in recycling the pie cabinet (or whatever) into a musical intrument which
actually plays music! Plus, if you don't have any real woodworking skills to start with, like me, your mistakes are cheap and enable you to improve your skills. I'm currently working on no. 8 - spruce top from a broken grand piano soundboard, and back, sides and neck from a mahogany shelf my parents were throwing out. I've spent money on a rosewood bass fretboard, which I think will make 4 soprano fretboards, but only because it will need that colour wood.
I know that if I bought the finest luthier materials I'd still be struggling to make a ukulele as good as a $150 Kala or whatever. Perhaps for no. 20 I might, but I'm more likely to search the local skips (dumpsters in American I think) for the satisfaction of finding a battered walnut coffee table.
The difference in my approach is that I'm doing this for fun. I don't ever plan to sell a uke, though I like giving them away (easy if you have less than $20 in materials in each one).
And I've learnt a lot of things. I can resaw tops, backs and sides by hand, and thin them by hand as well. OK, there's maybe 6-10 hours work in producing a soprano set, but done in 20 minute bursts it's very therapeutic. Hand bending on a hot pipe is frustrating as hell, but success is very satisfying. Plus I've got good at working out ways to salvage mistakes - with that much time invested you don't throw away a uke just 'cause your chisel slipped cutting the binding channel.
If the point is the finished instrument then I'd agree with you. But for me the journey is more important, and for that, recycling stuff is entirely appropriate. Plus you know your wood is properly seasoned - the grand piano was from the 1920s, and the wardrobe which supplies most of my necks to date was built nearly 60 years ago.