require price

functions.php

/* PRICE REQUIRED */
function wcv_product_price_required( $args ) { 
    $args[ 'custom_attributes' ] = array( 
	'data-rules' => 'required', 
	'data-error' => __( 'The price field is required- please add a price for your product.', 'wcvendors-pro' )
	); 
    return $args; 
} 
add_filter( 'wcv_product_price', 'wcv_product_price_required' );