In my humble opinion:
I think for a privateer - an Indy decaled, working sold privately would be $2900 to $3500.
Dealer prices will command a higher price, so I guess they can nudge closer to the $4000.
In 'as is' condition - is a gamble but sometimes will go in the buyers favor...Sometimes not.
There does seem to be a lot of parts for the Indy locally (TPF) - although quite a bit out of stock. Sight unseen - very tough call to price...I guess the key factor is are all boards present and does the playfield have wear?.
The market seems to be picking up a bit of late and I would probably put it on eBay with as many photos and thorough de-skription (spelt purposely) (including missing parts) at $0.01 start and let the market decide. You don't see many project Indys go on so would be very interesting to watch.