I haven’t personally come across a site specific to “paid” apps. Apple covers that territory, albeit rather poorly.
However my favourite source of any new app releases & reviews whatsoever is Matthew Willis – who has an awesome YouTube channel in Matt’s Apps. He covers both free and paid within his videos, but chooses to distinguish between ‘regular’ apps and games. Even ProductHunt seems to be getting crowded these days. But I sense it is difficult to be picked up (speaking without experience, for now)!
You’re also probably right in that there’s perhaps room & a need for a site to review top paid apps only. Especially if they were discounted briefly for their users 😀 However it pains me to think that developers believe free is the only way to go, paid apps still have a worthy place in the App Store.