How about this? We used to get inlet filters for Pari TurboBoy nebulisers ( part no 41E4852 ) for 54p each. Recently we needed to stock up on those and we were charged £2.60 EACH!!! We queried this with Pari and we were told that is the new price!!
Further to this, I have just learnt that the users don't like the cost of consumables and so we have now changed to a different make of nebuliser!

Thank God, there is no monopoly on nebs!