Wait for Deals on Current Apple TV
We expect the 4k Apple TV price to start at or above the current price for the Apple TV, which may translate into a better price for the current Apple TV. Even if you don't want to get the new Apple TV, you should wait to see what happens to the current Apple TV price.
We expect to see the price drop slightly, and you may even see some stores clear out stock of this model, depending on how Apple prices and positions the new Apple TV.
There's no reason not to wait for the new Apple TV release date to buy the old model based on price. The best case scenario is that it will drop in price to $129 or $99 as Apple tries to shift more people to the 4K HDR Apple TV.