Since 2005, all the couriers (TNT/DHL/UPS/FedEx) have stopped taking the fresh products like fresh truffles. Since then, the ONLY way to send the samples is by air freight like for the normal quantity shipments. By air freight, please note the following costs you may not 
be aware of:

1) For every shipment by air freight, no matter how big or small it is,  there is USD 55$ for export customs clearance and CCIB inspection cost.
2) For every shipment by air freight, no matter how big or small it is,  there is USD 10$ cost for Form A (certificate of origin).
3) The air freight rate:
below 10 kgs: USD 120$ which is the minimum freight cost charged by the air carrier;
11-45 kgs: USD 10$/kg
more than 45 kgs: USD 4.5$/kg which is the rate for the most of the main airport destinations in the world.
4) The air shipment is only air-freighted to the airports. As the consignee, you'll have to go to the airport to clear the goods and pick them up and the costs for this is not inexpensive.

Below are the costs for the sample ordering of 2 kgs, 5 kgs, 10 kgs, 20 kgs, and 40 kgs:

- 2 kgs of small size USD 15$/kg 

Product cost: 15x2=30$
Shipping cost: 120$
Export customs clearance and CCIP inspection: 55$
Form A: 10$
Total cost: 30+120+55+10=USD 215$
CNF unit cost: 215/2=USD 107.5$/kg

- 5 kgs of small size USD 15$/kg

Product cost: 15x5=75$
Shipping cost: 120$
Export customs clearance and CCIP inspection: 55$
Form A: 10$
Total cost: 75+120+55+10=USD 260$
CNF unit cost: 260/5=USD 52$/kg

- 10 kgs of small size USD 15$/kg

Product cost: 15x10=150$
Shipping cost: 120$
Export customs clearance and CCIP inspection: 55$
Form A: 10$
Total cost: 150+120+55+10=USD 335$
CNF unit cost: 335/10=USD 33.5$/kg

- 20 kgs of small size USD 15$/kg

Product cost: 15x20=300
Shipping cost: the gross weight including the outside packing is 23.32 kgs, the air freight rate is 10$/kg. The shipping cost is: 23.32x10=233.2$
Export customs clearance and CCIP inspection: 55$
Form A: 10$
Total cost: 300+233.2+55+10=USD 598$
CNF unit cost: 598/20=USD 29.9$/kg

- 40 kgs of small size USD 15$/kg

40 kgs already meets the minimum order quantity. For the quantity order, there is no more export customs clearance and CCIB inspection cost.

Product cost: 40x15=600$
Shipping cost: the gross weight including the outside packing is 46.64 kgs, the air freight rate is 4.5$/kg. The shipping cost is:46.64x4.5=210$
Form A: 10$
Total cost: 600+210+10=USD 820$
CNF unit cost: 820/40=USD 20.5$/kg

From the above costs calculations, the samples ordering of not less than 10 kgs is recommended.