Took a quick look on the NZXT site and they do not offer a separate panel for the Temptest 410. So it would probably be hard to find one anyways. Not sure if would fit either.

http://store.nzxt.com/case-side-panels-s/27.htm

If the side panel window is a big deal, I would look for a case that fits somewhere in between the two cost wise. The Source 210 is $30 right now, plus a windowed side panel would probably be $20-$30.

A case that comes to mind is the Corsair 300R Windowed.

http://pcpartpicker.com/part/corsair-case-300rwindowed

The Zalman Z9 Plus and Z12 Plus are some other options around the $60 price point.