How much does VIP level matter to you?
I’d judge it against the extra wagering, not set some monthly number for everyone. Even a $100 bump is just a number until you know what it takes to get there, say another $5,000 in action, and whether the house edge on that play eats more than the bump. Reload bonuses have the same issue, the offer amount doesn’t tell you much if the wagering attached to it is doing the work. If my normal play gets me a level anyway, then $20 or $30 back is still something. Raising my usual stake to get the level is where it stops making sense.