In 100 years, a pair of sequentially numbered R9s would be of collectible interest. In the meantime, in my opinion, the numbering is of no particular consequence.
I purchased my R9 because it was the smallest 9mm pistol then (and still) made -- an investment for the safety of my family rather than the growth of my portfolio. As far as investments are concerned (and in my unprofessional personal opinion), gold looks good for the long term (as always), energy stocks look promising for the medium term (possibly), and the stock of Ford Motor Company looks interesting for the short term (I know, but I'm a gambler at heart).