If your employer does have a license, then it does permit you to install a copy at home. Technically, it's defined as being for business use, but usually it's used as a personal, non-professional copy.
Sparkfun used to have an Arduino+LV student edition bundle for $50, but it seems to have been discontinued. I think if you get a Lego Mindstorms (which I think is $250) you can get LV for free so that you can use the toolkit, although according to this page, it looks as if you can download LV 8.6 even if you don't actually have an NXT - http://www.ni.com/white-paper/4435/en
There might be other options to get it (such as helping local schools with the various robotics competition, such as FLL), which should then probably qualify you to use the SE as a teacher, or other offerings like the one from Sparkfun. Also, if you have decent connections with your local NI office, they might be willing to give you an indefinite evaluation period in order to keep you personally using the software. You could also ask to join the LV beta and use that for free. There's actually a beta going on right now - ni.com/beta.
As for whether or not it's worth it, from a professional point of view, the factors for it would be if you think you can find work using LV in the future and if you want to stay diversified in order to be a better progrmmer (i.e. the more languages you speak, the more adapted you are to thinking about problems in different ways).
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