In Thailand, to find a "white elephant" means you are very lucky, so i would say the writer means you can find the rare gem in the shop.
3k baht for kapoo joint is quite high, usually means the girl is a top model there, not the normal pricing. At this price, the girl would be fully nude and session is 1hr. Some kapoo joints have different tiered prices for semi-nude.
The top up is for full service. 3k per shot is also quite ex, but if you add up the cost, it would be similar to what you pay for the higher class models at mid-tier MPs such as Labelle. At Maria or Black Caviar, the lower tier models would be at this starting price.
There are gems that can be found at kapoo. However, the difference at kapoo is that the lady gets to choose if they want to offer the FJ., and usually you have to negotiate with the girl or can ask the okt to negotiate upfront before choosing.
I know there are some kapoo that advertise full service upfront, but i won't consider these joints as kapoo though.
Finally, chances of kapoo girls offering FJ during this period is quite high. So good time to explore now
