I use DomainDiscount24.They don't charge you upfront to pre-reg a name.Additionally they only allow one person to pre-register a name.If they get it,you get it..there's no auction system like everywhere else.
The week before the release they charge you 1/3 of the registration fees.If they are successful they charge your card for the rest of the money,if not they will either credit your card or account.
They're touting thier 90% success rate in grabbing the German IDN .BIZ and .IDN .org at thier release.I pre-regged a high profile German name and they got it for me,so I'm pretty happy with them.I hope they're as good as getting .IN as they are BIZ and ORG.