How much does it cost to hardwire a hot tub

$20 -$20,000

:-)

There;s way to many variances to answer this.

You need to factor in How long it Takes to run the conduit, Crawl through the attic, under the house, GFI protection, 120 volt 20 amp, 240 Volt/60 amps, pulling the wire, any trenching. Basically add up the Hours in labor to acccompolish the above and the cost of materials.
If someone ran the conduit through attic, or trenched for me before I got there, it would not hurt my feelings, and would save you money.