Samara region had a sign-up bonus of 4 million rubles ($40000) until the last week: https://tass.ru/obschestvo/23024353

Other regions are comparable, 2-3 million rubles ($20000-$30000) are available in several more regions. Then there's a federal one-time payment of 500000 rubles ($5000) and a monthly salary of $2000.

Not exactly to get enrolled, but in Moscow websites officially advertize 2300000 rub to sign, which is about $25000. Then monthly payment is 190000 rub so for first year it'll be about $50000 which is 5 to 10 times more than average salary (depending on the region). Initial bonus for enrollment is city-dependent but as far as I understand anyone can just travel to Moscow and sign in there.

I heard that volonteer numbers right now are pretty high so army became more selective - people expect that war will end soon and hope to get sign in bonus without spending much time on the battlefield, if any.