The whole advertising industry is changing.
Things that used to work for some people don't anymore and the old things that didn't work are coming back with a new spin.
So, before you buy anything. Stop. Think about who you want to communicate with because that's what's going to define your answer.
If you're marketing to people 37 and under, Social Media is the best, least expensive answer if you work at being good at it. That said, if you put up automotive content and you're trying to network with women it may not be the thing that interests them enough to like you or comment on Facebook.
So, in this day and age, think about how to say something interesting to the people you want to come to your shop and keep the conversation going by facebook, twitter, google and even email. Many companies offer turnkey services for this that will cost you one to two dollars an hour.
Since the law says you can't email people without their permission (its called spam) then don't forget direct mail. A good list broker can find you lists to mail letters and postcards to. If you don't have or don't know where to find one, let me know I'll give you some references.
Postcard mailers can cost around a dollar each with 4 color printing postage, labeling and mailing. There are turnkey service bureaus who do that.
Remember, it's advertising. So don't do anything just once, don't rely on just one way to get your message to the market you want to serve and remember, no advertising you can buy is better than work of mouth.