whats the best way to advertise, and is buying traffic a good idea

Yes it will make you more profit , here is explanation
1) when you optimize your site with SEO, search engines (google ,yahoo ... ) will bring you free "targeted traffic" to your site
2) Spending money on ads can give you targeted traffic but for limited time , when you stop advertising there is no profit/sales

#1 first option is harder and time consuming but it will pay out
#2 easier and faster

I would suggest to go with both simultaneously , but for option #2 eg go with AdWords (facebook) spend $100 bucks on each if those $100 gives you profit in sales of $20 bucks so spending $1000 can give $200. Finally if you don't get profit from what you spent you already gained some knowledge which is also good invesment