Paris - München night train prices start at ~40€ for a regular 2nd class seat...for a bed in a sleeper prices start at ~90€. When travelling with an InterRail pass it is 9€for a 2nd class seat and 45€ in a 3-bed sleeper.
8 from munich to budapest
Additional costs esitmate when travelling with InterRail:
- 6€ for TGV Calais/Lille - Paris (It may be possible to avoid the TGV and go with free trains instead...I have to look at the ferry timings still)
- 9€ for a 2nd class seat in the CNL night train Paris - München (25€ in a 6-bed couchette, 35€ in a 4-bed couchette, 45€ in a 3-bed sleeper)
- München - Wien - Bratislava - Budapest: Free travel, no reservation needed
- I would recommend to go Budapest - Sofiya - Istanbul instead of going via Bukarest.
Budapest - Sofiya: 6bed couchette: 13,40€, 3bed sleeper 22€
Sofiya - Istanbul: same prices as above
So you will total at ~200 - 250€ depending on the comfort you choose.