This is why economics majors never get invited to orgies.
Just to give my 2CP (just enough to rent the lower half of an aging Half-Orc with no sexual skills!) on the cost of "companionship" issue it is thus:
First, it is no big secret that PC's in the average D&D game rapidly begin to operate on a financial level that is way beyond the comprehension of the average citizen. To the commoner, why a person would spend enough money on a potion that heals 1d8+1 HP (the same amount of damage the average person could heal by just spending a few days resting up) that they could live well on for a year and a half is just mind-boggling. This is what makes "adventurer" a separate class of individual in Eberron. To the average person, the life of an Adventurer is very nearly insane. They risk death on an almost daily basis for unimaginable sums of money that they then use to purchase items that have almost no usefulness in daily living but might (just might) extend their lifespan by a few months. KRAZY!
It is not primarily to this adventuring set that the "Ladies of the Night" in Sharn are catering. They cater (at the lowest levels) to the working stiffs (

) and sailors just in from the Dagger River. They cater (at the highest levels) to the power-elite of the city.
The problem (in my opinion) is that the range of prices reflected in S: CoT is that you see the "base rate" for "companionship" set at 5CP (in Sharn's Welcome) and a maximum price (in Firelight) of 12CP. That's just a bit over a doubling in price for services that I would imagine would vary rather substantially in quality and "class". The price range ought to (again, in my opinion) vary by at least an order of magnitude.
Am I going to restructure the "Cost of Companionship" price table in the book? No. Because I just don't think this is going to come up that often in the course of the game and when it does it is still a vanishingly small portion of the PC's total wealth. Even if I increased the price of the high end call girls by a hundred times it would be 12GP, which (at nearly 3rd level) is not an entirely trivial sum of money for the PC's but is still no big deal.
However, if the matter should come up again, I'll probably bump the prices of the "mid-range" hookers to 4SP or so and make the upper end be around 20SP. I think this helps to differentiate the services they offer from the whores who hang out in the alleys by the docks.
If I'd recognized this a bit earlier it would have lended a bit of realism to one of the plot points from the last adventure. It was understood that an NPC the party had encountered had gotten himself into financial trouble because of his penchant for making use of the services offered at Ellabella's. When the PC's got there and I read them the prices from the book they were like, "He spent himself into the poorhouse at 15CP a pop?! He must have been screwing 24/7/336! Did he have a limp when we first saw him?"
If I'd bumped the price to around 20SP then it might have made a bit more sense.