Yeah totally know where you come from with the SEO spammers.
I run an online store myself. I got nowhere with ads/flyers/mailers/etc. The only thing that brought up sales (and now its a proper business - so much so that I quit my day job) is organic ranking and traffic.
And I'm in a very competitive market in Asia. Web developers and marketing firms are a dime a dozen here, and I still outrank all my competitors who use other companies to do their marketing and SEO.
For a start in online marketing, you might want to try adwords and facebook ads, depending what you sell, it may get you some traction. But even with the best online store, google determines rank also based on engagement and bounce rate. You may have the perfect online store, but you wont rank as well as a competitor, because your design may or may not engage whatever traffic you get well enough.
All in all, I've been in this industry (as a professional web developer) since before the word SEO even existed. I've seen people get it wrong more often than they get it right, and I used that experience to turn my own business into a major success.
It's a maze of 'legends' and opinions when doing online marketing. I can only say, best of luck (you will need some of it haha).