Custom pricing logic we had running on our site to support legacy prices and sales.

gistfile1.php

<?php
// This is an excerpt from *some of* the custom pricing logic we had running on our site to support legacy prices and sales.
// Our current custom pricing script is about 140 lines long.
/*
	If purchasing PMPro Plus and they've had plus or core in the past,
	calculate the appropriate price.
*/
if($level->id == 20 && is_user_logged_in()) {
	// If the user has a current subscription, use the billing amount on file.
	$user_level = pmpro_getMembershipLevelForUser();
	if( pmpro_hasMembershipLevel( 20 ) && pmpro_isLevelRecurring( $user_level ) ) {
		$level->initial_payment = $user_level->billing_amount;
		$level->billing_amount = $user_level->billing_amount;
	} else {
		// Check if they had a discount in the past.
		$paid_47 = $wpdb->get_var("SELECT id FROM $wpdb->pmpro_membership_orders WHERE user_id = {$current_user->ID} AND membership_id IN(6,20) AND total IN('47', '47.00') AND status NOT IN('refunded', 'token', 'error', 'review') AND timestamp < '2017-08-30 00:00:00' LIMIT 1");		

		if($paid_47) {
			$level->initial_payment = '47.00';
			$level->billing_amount = '47.00';
			return $level;
		}

		$paid_97 = $wpdb->get_var("SELECT id FROM $wpdb->pmpro_membership_orders WHERE user_id = {$current_user->ID} AND membership_id IN(6,20) AND total IN('97', '97.00') AND status NOT IN('refunded', 'token', 'error', 'review') AND timestamp < '2014-08-30 00:00:00' LIMIT 1");
		$paid_147 = $wpdb->get_var("SELECT id FROM $wpdb->pmpro_membership_orders WHERE user_id = {$current_user->ID} AND membership_id IN(6,20) AND total IN('147', '147.00') AND status NOT IN('refunded', 'token', 'error', 'review') AND timestamp < '2017-08-30 00:00:00' LIMIT 1");
		$paid_197 = $wpdb->get_var("SELECT id FROM $wpdb->pmpro_membership_orders WHERE user_id = {$current_user->ID} AND membership_id IN(6,20) AND total IN('197', '197.00') AND status NOT IN('refunded', 'token', 'error', 'review') AND timestamp < '2017-08-30 00:00:00' LIMIT 1");

		if($paid_97 || $paid_147 || $paid_197) {
			$level->initial_payment = '147.00';
			$level->billing_amount = '147.00';
		}
	}
}