I recommend removing the word "cheap" from your landing page. I understand the sentiment (and love it), but what may be "cheap" in one part of the world is likely "expensive" in another. It also cheapens (no pun intended) your value proposition from an enterprise perspective. Be confident and drop the word.
Also, perhaps in some fine print (or even better - a clearly visible and simple explanation) defining the scope of the perpetual license -- limited to +K (where K ≤ 0) major software versions or all future releases (K = ∞)?