Good website to find affordable Pokemon TCG sets?

As of recently, Destined Rivals became one of the many recent sets that sold out way too quickly and got affected by scalpers and such. This also means that trying to find affordable English TCG sets has become a near impossibility without finding price gouged ETBs and out of stock products. But since I am hoping to get some Pokemon cards soon, I am wondering if there are any good websites that still sell affordable Pokemon TCG sets (i.e. finding Booster Boxes less than $50 or finding Elite Trainer Boxes less than $100?