Instruct: Classify the given Amazon review into its appropriate rating category
Query: Ever increasing price for these exceeds cost of full system

I am annoyed with the price fluctuations on this product, sometimes it is extremely reasonable and other times it costs more than getting a whole new filtration system. I have researched alternative filters in great depth and I have not found any other ones that are compatible with this system. I did not replace it yet because I it is really great for my cats' preferences and I hate to waste plastic for no reason, but I will avoid the brand next time.