What is the cost per MB with a pay-per-use plan?

You can choose between two types of pay-per-use plan: a pay-per-use plan without a subscription fee (for Personal and Business customers) and a pay-per-use plan with a subscription fee (for Business customers). 

Pay-per-use plan without a monthly subscription fee
PERSONAL CUSTOMERS
For Zone 1 countries (including Italy, the rest of Europe, the United States and many other countries), the plan’s pay-per-use rate is €0.12/MB if you use more than 2 MB/month and €0.24/MB if you use less than 2 MB/month. See here for details of the other zones:  https://www.thingsmobile.com/private/plans
When data traffic is used by a SIM card, the minimum charge is 1 MB/month. If no data traffic is used by a SIM card, there is no charge.
The default multi-operator profile (TM-1) is assigned during the activation process. It costs €0.25 per SIM card to change a roaming profile.
Traffic is charged in increments of 1 kB, except for in the following countries: Bahrain, Brunei, Cuba, Equatorial Guinea, The Gambia, Israel (Hot Mobile), Laos, Malawi (Telekom), Malaysia (Celcom), Moldova, Oman, Pakistan (Warid), Russia (VimpelCom), Sri Lanka (Mobitel), Sierra Leone, Vietnam (10 kB); Iran (20 kB); Qatar (Ooredoo) (30 kB); Pakistan (Pakistan Mobile) (100 kB); Tajikistan, Uzbekistan (1024 kB).
The rates include VAT where due.
BUSINESS CUSTOMERS
For Zone 1 countries (including Italy, the rest of Europe, the United States and many other countries), the plan’s pay-per-use rate is €0.10/MB if you use more than 2 MB/month and €0.20/MB if you use less than 2 MB/month. See here for details of the other zones:
When data traffic is used by a SIM card, the minimum charge is 1 MB/month. If no data traffic is used by a SIM card, there is no charge.
The default multi-operator profile (TM-1) is assigned during the activation process. It costs €0.20 per SIM card to change a roaming profile.
If a SIM card is not used for more than 12 consecutive months (no data traffic and no incoming and outgoing SMS messages), a charge of €1 will be taken out of the remaining credit.
Traffic is charged in increments of 1 kB, except for in the following countries: Bahrain, Brunei, Cuba, Equatorial Guinea, The Gambia, Israel (Hot Mobile), Laos, Malawi (Telekom), Malaysia (Celcom), Moldova, Oman, Pakistan (Warid), Russia (VimpelCom), Sri Lanka (Mobitel), Sierra Leone, Vietnam (10 kB); Iran (20 kB); Qatar (Ooredoo) (30 kB); Pakistan (Pakistan Mobile) (100 kB); Tajikistan, Uzbekistan (1024 kB).
The rates do not include VAT where due.
Pay-per-use plan with a monthly subscription fee
BUSINESS CUSTOMERS
For Zone 1 countries (including Italy, the rest of Europe, the United States and many other countries), the plan’s pay-per-use rate is €0.02/MB. See here for details of the other zones: https://www.thingsmobile.com/business/plans/pay-per-use-plan-with-subscription-fee
With this plan, there is a monthly fee of €1 per SIM card.
The default multi-operator profile (TM-1) is assigned during the activation process. It costs €0.20 per SIM card to change a roaming profile.
Traffic is charged in increments of 1 kB, except for in the following countries: Bahrain, Brunei, Cuba, Equatorial Guinea, The Gambia, Israel (Hot Mobile), Laos, Malawi (Telekom), Malaysia (Celcom), Moldova, Oman, Pakistan (Warid), Russia (VimpelCom), Sri Lanka (Mobitel), Sierra Leone, Vietnam (10 kB); Iran (20 kB); Qatar (Ooredoo) (30 kB); Pakistan (Pakistan Mobile) (100 kB); Tajikistan, Uzbekistan (1024 kB).
The rates do not include VAT where due.
You can find more information at thingsmobile.com