I like your question.
Same thing I've been asking myself several times.
You can invest your time in SFI: read,learn evrything is for FREE here.After you comprehend all those things ,you can start growing your business.
Then is good time to invest some money in it:how much,depend of what you want acomplish.
You can buy things on TripleClics ( TCredits is the best investment for me ),pay for advertising
and more ,and more....