... you might also be able to make do with machine built wheels ...
That's the dilemma, isn't it? I can spend $500-$600-$more-$$even more on a dynamite set of wheels that could last me for years but if I find that touring doesn't really resonate with me, or I find out that I'm really only interested in doing 3-4 day weekend tours a few times a year, then I've spent money I didn't need to. Or I could spend that much and find out that touring is a true passion and I could take the wheels with me to a new, proper touring bike and get years of service out of them.
On the flip side, I could spend $200-$300 on a "decent" set of wheels that might be all I'll ever need for 3-4 day weekend tours a few times a year, then find out I really want to do long tours several times a year (and maybe a cross-country one day) and have to upgrade the wheels to something way more durable. But I've just answered my own question ... if I get THAT serious about touring, I'll likely need/want a true touring bike - not a hybrid that I've upgraded to just "make do" status. Getting the "right" wheels would be part of the whole package of buying a touring bike.
Now ... if I could just hit the lottery (or grow a money tree or find the Fountain of Youth or ...).