Q:

How to secure consumer info without buy an certificate?

I need to know how to properly secure my consumers credit card info without buying expensive certificates?  It is possible to use https:// and ssl or tls without an certificate and without scary warnings from browsers ?
If yes what is the safest way ?

A:

I need to know how to properly secure my consumers credit card info
  without buying expensive certificates?

RapidSSL certificates are as cheap as $49/year. Furthermore, properly securing credit card information requires a lot more than just using TLS and having a CA signed certificate.
If $49/year is a lot of money to you then I don't think you have the resources to properly store credit card data in a secure and compliant way. Presumably you are using free or very cheap web hosting which means you probably have a shared hosting environment with limited control over your firewall, logging, and other potentially malicious users on the system.
Having such limited resources does not mean you can't accept credit card payments, just don't host the checkout or store credit card details yourself. Check with your bank to see if they have a hosted gateway product, or look at something like Stripe Checkout or PayPal express checkout. 
These will allow you to accept credit card payments without needing to use TLS (although I still recommend that you do), because your system will never come in contact with credit card data.

A:

I need to know how to properly secure my consumers credit card info without buying expensive certificates? 

Use a payment provider and don't handle any sensitive information like credit cards by yourself, that is don't even get the information from the user. 
Since you are unable to invest even a comparable small amount of money to get a proper certificate you will not be able to invest the much larger amount which is needed to build a infrastructure for securely handling such sensitive data. The certificate used for SSL only cares about transport security from the clients browser up to your server. But in no way it will make you shop protected against attacks like SQL injection or hacking of your server.
If you are still willing to handle credit card data by yourself you should have a look at the PCI requirements for handling credit card information. The costs of the certificate are small compared to the other costs needed to reach PCI compliance.

