Payment Gateway in Wordpress

I am currently making a crowdfunding website using the backer theme(Wordpress) from themeforest.com. I have purchased the theme but now I am facing problem in integrating the payment gateway on it as it is crowdfunding payment where different customers will contribute a little towards the total required amount on the same project. The theme has mentioned in its description that it can be done by adding ignition deck plugin but the plugin is too costly. Is there a way I can do the same without using the plugin? Here is the link of the theme: http://ift.tt/1SBXg5P

via Chebli Mohamed