There are two ways to get traffic to your site:
1) Make your site Search Engine friendly and submit it to all major search engines.
You are not required to pay anything to search engines for this.
2) Advertise on Cost Per Click text ads on
To get your ad displayed on Google & Yahoo will require you to bid high, that may not be very feasible at this stage, as with the season coming up, bids for ads would shoot up further, and I don't think this would be a viable option as you are looking for traffic at a low cost.
Advertising on sites like 123greetings.com is cheap. Further, the traffic on this site is likely to be more conducive as the traffic is young, looking for options like the ones on your site. Conversions are likely to be better from 123greetings.com.
Take a look at the following links where I think you have your target audience:
To sign up, use the following link:
I shall be glad to be of any help.