Google search appliance has been discontinued recently. Check out Google search appliance (GSA) pricing in this blog.
Google search appliance (GSA) pricing below
GSA pricing
Documents
Queries per day
Appliances
Search Response time
Disaster recovery
Spell check
Phonebook whos who
SAP Enterprise portal
Corporate intranet site
$45,000
per year
50000
upto 10000
2
Less than 1 second
minutes

This information has been extracted from the document titled Improving Your ROI with Google Enterprise Search.
This particular table showcases the Google search appliance pricing
