Build a good name by word of mouth: you spend nothing and it resonates much better with potential customers.
The best I've seen so far was like a 2 year payback period. Not very good. It's gotten competitive enough that I'm rarely seeing Adwords be useful anymore to a startup.
Our ads convert to signups at about a 10% rate. At $0.16 CPC, that means we pay $1.60 for each signup via Adwords. That's still too low for us to get a reasonable return.
I've tried various things in order to bring up the conversion rate, since I think 10% is low, but this is an area where I'm lost. I've tried making a landing page, A/B testing the landing page, and some other tricks, but I'm out of my area of expertise here. That's what I meant when I said that doing ads is pretty damn hard.
But if I could just hit 20% conversion and stay there...then we'd be golden!
game A: spent $100's on Google ads ... made $0 revenue
game B: spent $0 on Google ads ... made $100's revenue
(disclaimer about other variables, YMMV, take with grain of salt, etc.)
I especially liked the point of not blowing money on ads and such. Getting ads right is hard, and most times you will waste your ad money. Feel free to dabble, but realize that your ROI will probably be dismal. Make sure to track your ROI somehow, or you won't even know how badly you're doing.