I didn't really get the 'paid dating' vibe at all. I just took the expensive comment as a joke.
It felt really obvious to me. Gals invest a lot of money into their appearance and are already known to partake in enko (schoolgirl prostitution/paid dating) to afford their lifestyle, so her cutting her nails (rip) + the comment is a pretty blatant implication. It doesn't help that the paying lady is an OL, as the stereotype is that office workers are the most common customer for enko.
I feel like the last panel is a time skip forward. And to support the non prostitute argument, I feel like gyaru wouldn't cut her nails short for someone she's being paid to sleep with, since the long bright nails are part of her gyaru aesthetic. If she were being paid, I feel like gyaru could get away with just lieing there and letting ol do all the work
Yeah, but by that token, it is also unlikely she would cut her nails for what is basically a one-night (day?) stand with a woman she just met on a bus station. That sounds far more unlikely than her being paid for it, to be honest. The fact she had to clip her nails to begin with shows she is obviously not a regular at using her fingers to satisfy ladies.
I think the prostitution angle was pretty blatant here. Regardless, it was nice and criminally short, lol.