I'm interested in the NWGS. My friend, who I make knives with, wanted to have something wider, stronger, and more reliable. How much did the sander cost to make? Was it easy or hard?
Tracy has put together a very good set up plans, and as far as the ease of build, I'd say it's fairly straightforward. If you can make a knife, you can build a NWGS. As for cost, I wanna say that I had about $650 or so into mine altogether, but I also bought an 8" contact wheel from Beaumont Metal works, as well as 2 idlers, a drive and tracking wheel, which added up to a pretty big chunk, or probably more than half the cost of the build. Now days there are more options available on eBay and such, for a bit less money, and if you just start with a flat platen with aluminum idlers, it's not nearly as much as a contact wheel.
http://www.mickleyknives.com/No-Weld-Grinder/no-weld-grinder.html
Tracy gives a pretty accurate price breakdown on his website, and it's actually lower than I remembered for a used or "scavenged" build. Looks like you could build one for $300 or less (just a flat platen that is) if you try to source all your parts on the cheap. Really, I'd hazard to guess that even $250 could be doable.
DISCLAIMER: As with anything, the results you get will only be equal to the work put into it. While it's a fairly straightforward build, some care must be taken to have holes drilled square and properly located, cuts made square and straight, wheels lined up with each other, etc.... Also, I might add that I changed a couple of things from how the plans have them, including using a heavier base tube, spacing the pillow blocks out more, using heavier "straps", and one or two other things to kind of beef it up. I've made a few videos on my youtube channel over the years as I've modified or upgraded things, so you might take a look before you build, but as the plans sit, they are still quite good, and more than adequate for a nice robust machine.