To find an 0603 resistor within 30% of 2 kiloohm:
./resistor 2k --tolerance 30
To find any capacitor within 10% of 1nF with a minimum voltage of 20V:
./capacitor 1nF --voltage 20 ./capacitor 1nF --voltage 20 --package ANY
Click the printed URL. Results are priced according to a quantity of 10 and sorted by ascending price, so you can probably use the first result.
The cheapest part number is printed.