Yes I tried Google shopping campaign for a client eCommerce site. and it is very helpful in generating leads. All you need to do is create a Google Adwords account and set up shopping campaign through it. If you master the art of writing creative and eye catchy lines for your ad, then you can set up the campaign in a matter of time.
The simple and the best way is using a captcha plugin. It worked best on my website have a look at any good rated captcha plugin and install it in your website.