Come on Mark! There is no such thing as too old ;) 

I'm older than you and I feel as if I just started my life (,")

I'm still thinking what new language I would like to learn, I don't mind being a learner all my life and I believe I can do that at any age, it's a matter of perseverance. Good luck

I agree with Mumtaz. The age is not important when it comes to learning a new language. I have been studying Russian for three months and I sometimes feel like quitting. However, when I learn a new word or phrase I feel much better. Besides, Spanish is not that difficult. Good luck!

I'm in my sixties and trying to learn Spanish. I think I'm making slow but steady progress. It's tough. I've been doing it for about 1-1/2 years now, maybe averaging an hour a day.

I don't think my pronunciation is too bad, vocabulary seems relatively easy, but grammar is very very slow-going.

One of my modest goals is to post a notebook entry here and have it come back without any corrections at all, and that hasn't happened yet even though I keep posting shorter and simpler entries.

There's no doubt that something is sinking in. For example I will sometimes--not always but sometimes--hear Spanish and be aware that I have caught the meaning without translating it into English.

Having all this written, I think that what you've said is just a nonsense:) You are in an ideal age. Better you've started in the age of 5 if and only if you acquired Spanish by the most productive (still the most productive. by the way) and natural way: diving into it.
But are you sure that you need just the result and you need it cheap? What about side-effects of the process and all the side-knowlege? What is it helps to keep your brain fit after all?! Being a bilingual child would never make you clever, nor educated, you'd just have an additional skill.

Whenever you think you are.