(Some of these gals also put an ad on: backpage.com) Amber Costello did. (one name she used was: "Carolina")
Regarding Amber Costello, the "$1500" amount that was mentioned:
I found online, about some of the actual ads that were placed by the gals (on backpage.com),
and the common amount for an "overnight stay" was: "$1500" (some gals charged, "$2,000", for an "overnight stay")
It goes without saying that: This "serial killer" did not pay these victims. (He could "say" anything.)
Even "if" he did pay them at the beginning (before he killed them), you know good and well that he then got the money back from them.
(i.e., you know that this guy was getting "freebies") (and he could "say" anything)
He possibly "told" all of his victims, that he would give them "$1500"
(which was the common amount for, an "overnight stay")
"Saying" an overnight stay, would also be to HIS benefit.
(Reason being: Well say that the gal told her boyfriend, friend, or whoever, that she wouldn't be back that night. Noone would suspect anything, until she didn't come back home, the "next" day.) This scenerio gives the killer some "time", before anyone starts suspecting anything.
But anyway, this shows that the amount of: "$1500",
was (& most-likely, still is) commonly-stated by gals (who were prostitutes),
for,
an "overnight stay".