From the Nepal side.
Kanchenjunga, meaning “five great treasure houses of the snow,” is the third-highest mountain in the world and the second-highest in Nepal. Until 1856, it was believed to be the highest of all.
$3-$5,000 for an up to a 28 day adventure according to one source.
You could do it cheaper by shopping around in Kathmandu. Doing more of the organizational work on your own.