displaying certain payment methods for customer groups

you can do this using magento event observer,create an event on payment_method_is_active and depednds on customer group disable and enable payment method:

check this link: Implementing payment method per currency

and you need do on some change in observer.php I have trying to example and try to modify according to you

   public function filterpaymentmethod(Varien_Event_Observer $observer) {
        /* call get payment method */
        $method = $observer->getEvent()->getMethodInstance();
if(Mage::getSingleton('customer/session')->isLoggedIn()) {

 $roleId = Mage::getSingleton('customer/session')->getCustomerGroupId();
 $role = Mage::getSingleton('customer/group')->load($roleId)->getData('customer_group_code');

      if($method->getCode()=='purchaseorder'){
            $quote = $observer->getEvent()->getQuote();

            if($role == $yourcustomergroupid){
              $result = $observer->getEvent()->getResult();   
              $result->isAvailable = true;
              return;
            }else{
               $result = $observer->getEvent()->getResult();   
               $result->isAvailable = false;
            }
        }

     if($method->getCode()=='checkmo'){
            $quote = $observer->getEvent()->getQuote();

            if($role == $yourcustomergroupid){
              $result = $observer->getEvent()->getResult();   
              $result->isAvailable = true;
            return;
            }else{
              $result = $observer->getEvent()->getResult();   
              $result->isAvailable = false;
            }
        }
}

}

Note: If you not getting customer group id from session then you need tp load customer by customer id(which is must get from session) for getting customer group from session try below:

https://stackoverflow.com/questions/9242390/showing-which-group-a-customer-belongs-to-in-magento http://xhtmlandcsshelp.blogspot.in/2010/12/get-customer-group-id-in-magento.html

Let me know if you have any confusion

You can use the extension and its working fine for customer group and also filter by product and its free:

http://www.magentocommerce.com/magento-connect/paymentfilter-for-products-and-customer-groups.html

In Magento 2

Let’s create a module. Step 1) Create folders like this.

app/code/Pits/PaymentMethod/etc/
app/code/Pits/PaymentMethod/Observer/

Step 2) Declare your module

app/code/Pits/PaymentMethod/etc/module.xml.

Paste the following code in the above file.

    <?xml version="1.0"?>
    <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="Pits_PaymentMethod" setup_version="2.0.0" /></config>

Step 4 ) Create registration file. app/code/Pits/PaymentMethod/registration.php Paste the below code.

<?php
\Magento\Framework\Component\ComponentRegistrar::register(
    \Magento\Framework\Component\ComponentRegistrar::MODULE,
    'Pits_PaymentMethod',
    __DIR__
);

Step 5)Run the below command in the command line

php bin/magento module:enable Pits_PaymentMethod

 php bin/magento setup:upgrade

Step 6)Lets create events.xml file

app/code/Pits/PaymentMethod/etc/events.xml

Paste the below code in it.

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="payment_method_is_active">
        <observer name="Pits_PaymentMethod_DisabledPgByCustomergroup" instance="Pits\PaymentMethod\Observer\DisabledPgByCustomergroup" />
    </event>
</config>

Step 7)Lets create observer file

app/code/Pits/PaymentMethod/Observer/DisabledPgByCustomergroup.php.php



<?php
namespace Pits\PaymentMethod\Observer;
use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\App\Request\DataPersistorInterface;
use Magento\Framework\App\ObjectManager;
class DisabledPgByCustomergroup implements ObserverInterface
{
    public function __construct(\Psr\Log\LoggerInterface $logger)
    {
        $this->_logger = $logger;
    }
    /**
     *
     * @param \Magento\Framework\Event\Observer $observer
     * @return void
     */
    public function execute(\Magento\Framework\Event\Observer $observer)
    {
        $result          = $observer->getEvent()->getResult();
        $method_instance = $observer->getEvent()->getMethodInstance();
        $quote           = $observer->getEvent()->getQuote();
        $this->_logger->info($method_instance->getCode());
        /* If Cusomer  group is match then work */
        if (null !== $quote && $quote->getCustomerGroupId() != 4) {
            /* Disable All payment gateway  exclude Your payment Gateway*/
            if ($method_instance->getCode() == 'purchaseorder') {
                $result->setData('is_available', false);
            }
        }
        /*else{
        if($method_instance->getCode() =='purchaseorder'){
        $result->setData('is_available', true);

        }
        }*/
    }
}

Step 8)Run this in command line

php bin/magento setup:upgrade