50% are male, so if it's half the cost, then overtime it will even out, yes. You can get lucky, bad or good, in short-term.
If you need 100 plants, you'd want to plant a bit more than 200, i'd say. The larger the batch the closer you can get be to 'double', but with smaller batches you'll have greater volatility and need to plant more than double if a specific number is required.
you can look up the math for this probability. it's an easy context. depending on how many you need, you can be X% confident you get that many or more females based on how many you germinate. obviously, you want to be high-90's confident or even 99%. i'm not doing that grunt work, lol. It's monkey-see; monkey do it-level of stuff.