// Set a minimum dollar amount per order
add_action( 'woocommerce_check_cart_items', 'spyr_set_min_total' );
function spyr_set_min_total() {
	// Only run in the Cart or Checkout pages
	if( is_cart() || is_checkout() ) {
		global $woocommerce;

		// Set minimum cart total
		$minimum_cart_total = 500;

		// Total we are going to be using for the Math
		// This is before taxes and shipping charges
		$total = WC()->cart->subtotal;
		
		// Compare values and add an error is Cart's total
	    // happens to be less than the minimum required before checking out.
		// Will display a message along the lines of
		// A Minimum of 10 USD is required before checking out. (Cont. below)
		if( $total <= $minimum_cart_total  ) {
			// Display our error message
			wc_add_notice( sprintf( '<strong>A Minimum of %s %s is required before checking out.</strong>'
				.'<br />Current cart\'s total: %s %s',
				$minimum_cart_total,
				get_option( 'woocommerce_currency'),
				$total,
				get_option( 'woocommerce_currency') ),
			'error' );
		}
	}
}