Cheaper parts are typically made of inferior materials and have a shorter lifetime. Lesser filtration material will also decrease the filter’s efficiency, allowing particles to penetrate into the air net. Cores not made of stainless steel might corrode and collapse during operation.
Even if an alternative cartridge fits, it hasn’t been designed specifically for Atlas Copco and will therefore not be a 100% match. This could cause a higher pressure drop and increased energy consumption. That could results in a higher total lifecycle cost of your compressed air system.