Your very best bet is to make that copycat version to taste at home. Once you taste the homemade gray stuff, it’s not likely you will feel any need to spend money on it in WDW. Yes, it tastes the same.
It is not awful. It is not delicious. It just has far more marketing power than it could ever deserve. Like Disney Krispy Treats. Buy a box of rice crisp cereal and a bag of marshmallows and have a big ‘ol pan of them, decorated any way you like. You can even hand-shape some Mickey heads.
Actually, making both treats at home can be really fun activities or treats leading up to your trip, or help you keep happy vacation vibes after you come come.