I realize that depends on the persons specific situation...BUT...for a person in their late 60's with a sound "normal" investment portfolio...would $5-10K be too much to invest at this time...knowing the big bang is 10-11 years away?
I would get at least 2k shares if I were you, wouldn't want to get caught with less than that if/when onvo takes off. Nice to hear of someone nearing retirement age seeing the potential in onvo, not just us young folks. I'm 21 and have about 2k shares so you don't want to have less than me :)
Look at it from a different # perspective as a % of your total portfolio. Think "how much am I willing to risk without having a major freakout?" For example, let's say you have $20K in your portfolio overall and are ok risking up to 25% on stocks, but want to maintain 75% diversified/safe. If that's the case, then be super risky and either put a whomping 25% in ONVO and hold for 5-10 years to become rich, or spread out your 25% across ONVO and other stocks. I put a big chunk of $ in ONVO, probably too much. But I'm a firm believe that to be very successful you have to take some very big risks!
I'm holding for 5-10 years and literally have no idea how this stock could stay below the $20 price point in the next 3 years, so I'm hoping for a 300% return, or greater.