Monetary wedding gifts

How much do you usually give? This girl is my older sister figure so I'd like to be generous but also want to be reasonable. Her best friend suggested 200 and a small sentimental gift. My parents are giving her 1000 and I'm over here clueless. Mum thinks I shouldn't have to give that much as I'm sort of included in they're giving her a large amount but I feel like 200 is too little.