Good luck finding WC burundi.
TR price will vary greatly within an area.
Its not unheard of for a petstore to ask for $150 for a male of that size, $100 asking at that size is fairly common.
Do they get it?
Not sure, rare to see a frontosa that big in a petstore, alot 7-9 inchers though for that price.
A private seller, should be able to move it for about $40 to $75, if you can move it, though thats a nice size fish, they are not uncommon.
Auction, depends who shows up to the auction.
I have not seen a frontosa that size at auction at any of the cali fish clubs, but i have seen moba fry go for $5 then another time, smaller go for $40.
Price at auction really depends who shows up, or if aquabid, who happens to search that week.
so if you are selling, $40 should move it fairly quickly. $75+ you'll have to sit on it for awhile.
IF you are looking, Store will run you about $100.
private breeders, depending on how much they are trying to get rid of it, $40-75.