Best Buy lowered the price on all of the older PS4 PlayLink titles to $4.99 each ($3.99 if you still have GCU). Additionally, you can save another $1 off each one if you change your order from shipping to in-store pickup during checkout. So, if you still have GCU these can be $2.99 each.
Hidden Agenda:
https://www.bestbuy.com/site/hidden-agenda-playstation-4/9079109.p?skuId=9079109
Knowledge is Power:
https://www.bestbuy.com/site/knowledge-is-power-playstation-4/9045114.p?skuId=9045114
That's You:
https://www.bestbuy.com/site/thats-you-playstation-4/9083009.p?skuId=9083009
Singstar Celebration:
https://www.bestbuy.com/site/singstar-celebration-playstation-4/5360501.p?skuId=5360501
Hidden Agenda:
https://www.bestbuy.com/site/hidden-agenda-playstation-4/9079109.p?skuId=9079109
Knowledge is Power:
https://www.bestbuy.com/site/knowledge-is-power-playstation-4/9045114.p?skuId=9045114
That's You:
https://www.bestbuy.com/site/thats-you-playstation-4/9083009.p?skuId=9083009
Singstar Celebration:
https://www.bestbuy.com/site/singstar-celebration-playstation-4/5360501.p?skuId=5360501