Meanwhile, non-graded cards are cheaper and better for casual collectors or players who are not focused on investment
You can also perform some cool loops with your frog commander, Dakmor Salvage, a free discard outlet like Noose Constrictor, and a way to shuffle your graveyard into your deck like Kozilek, the Great Distortion to draw your entire deck and end the game in a single turn
Your best bet is to always separate them and only include them if the buylist has a specific category for them
An expansion's face Pokemon does tend to see its rainbow rare in the top ten somewhere (Evolving Skies had rainbow Rayquaza VMAX, while Chilling Reign had Shadow Rider Calyrex VMAX), but even then Mew VMAX is worth a lot more than expected thanks to its dominant role in the game's current Standard format
And with the help of the Level 4 monsters, you can even switch him out and bring him back in during the opposing turn, even giving you another disruptive option