If there is "special price (Advanced Pricing > Special Price)" of, for example, of 2 dollars and a normal price of 10 dollars, this will be indexed over but will show up on the front end as the 10 dollars crossed out with the 2 dollars showing.
If there is a fixed price for a group it will be indexed over. For the group price (i.e. Advanced Pricing > Customer Group Price), if there is a group price of "fixed" that is some number of dollars dollars, it may be indexed over like this:
price{
USD:{
...
group_1_tier_formated:
"$100.00"
...
}
}
It will render under the condition specified here for autocomplete and here for the instant search hit.
If there are multiple of a group, the lowest price is indexed over. I.e, if there are multiple fixed prices for a group, the lowest prices is by default indexed over.