The cheapest guided option is an open group truffle ceremony at about €650 per person. This all-in price typically includes guidance, preparation, integration, meals, drinks, and an overnight stay.
There is a fund that can lower the price to roughly €250 per person for some low-income participants, depending on eligibility such as an income below €30,000 gross per year and the availability of the fund. I cannot verify current availability.
For a private experience, an at-home session starts around €850 for trained practitioners plus €0.50 per km travel, without meals or an overnight stay. If you do not have your own location, a private session in Den Bosch at De Bedding is often the best total-price deal at about €850 including location and an overnight stay.
For dates, eligibility notes, and what is included, see the organizer’s open group ceremony page. Hope this helps you choose the most budget-friendly option.