At Golden Crown the minimum deposit is A$30 and the minimum withdrawal is A$45 (terms 10.4 and 11.1). Deposit A$30 and lose a little, and you can’t withdraw the rest until you’re back above A$45.
Turnover rules
VegasNova requires deposits to be wagered at least once before any withdrawal (§4.22). Bonus money carries its own, larger requirements.
Crypto minimums differ
Golden Crown lists separate crypto withdrawal minimums (for example 0.0012 BTC) in clause 11.1; the A$ value of that moves with the coin price.