To be more specific, this Cash Vault costs 260 Estate Cash to purchase, and from then on can be collected once per week. If you forget a week, your "year" of Estate Cash bonuses will simply extend, and you won't lose anything in the process. Each week, you'll simply be able to collect 10 Estate Cash from the Cash Vault, until you've collected 52 times, for a total return of 520 Estate Cash, which is double your original investment.
We'd never say that the original investment price of 260 Estate Cash was cheap, but if you're a diehard player that will likely spend that same amount of money within a year's time anyway, it makes sense to at least consider this as an investment. Whether or not you ultimately purchase it, of course, will remain up to you.
Will you purchase a Cash Vault in Hidden Chronicles, or will you continue to simply purchase Estate Cash only when you really need it? Sound off in the comments!