Dick - I've found from extensive purchasing and repair experience in another field, that businesses who pull this stunt, have only about 3 things in mind when they quote outrageous prices ...
1. They're not really interested in the repair, so they quote high, on the basis they care not a whit, whether they get the job or not ..
2. The item is obsolete or becoming obsolete, so they charge excessively to ensure you buy the replacement product ..
3. They think you are a captive customer and they think you can't go anywhere else ..
I would investigate other instrument repairers who have the capability to do the repair, or change the indicator to another brand.
You could also investigate the possibility of acquiring a complete replacement unit from an aviation spares supplier. There are 7 x 160E105-3's listed below, try an RFQ and see if the quotes are sensible.
Avspares.com - parts search