The 9.7 model goes for $400, the smaller 8 tablet can be had for $350. The official Samsung site has no-interest payment plans (6 months) for $66.66 and $58.33 respectively. Another option is getting an Open Box unit from Best Buy at $328 and $297 respectively.
The Galaxy Tab S2 is from 2016, but the Super AMOLED screen and Snapdragon 652 chipset have aged gracefully. These two even got Android 7.0 Nougat in April. Note that this is for the Wi-Fi models.
Check out the table below for links to the online stores (again, US only).