Antonio made a good point about the word 'cheap' being demeaning.
Also bear in mind that the minimum legal wage in the UK is 10 euros per hour. If you pay someone only 8 euros for 90 minutes, that is around half the minimum wage. Taking into account the added time for preparing lessons and the fact that italki takes a sizeable commission from the lesson fee, a teacher who is desperate enough to accept these terms would be working for almost nothing.
These are challenging times for all of us. But lowering prices is not the way to help each other or help the economy. We all need to be kinder, more helpful, more patient, more accommodating and more flexible in these difficult days; we should not be taking advantage of others by devaluing their time and skills.