After further research and returning memories I would recommend to give credits.

I don't know to whom the original method belongs to but the switch itself is also told on Anthony Lindans Redonkulous.
There is one new (good) addition to it which max came up with.

Now to be complete honest iam not sure if it justifies the price.

Also for the serial bill divination you may consider a different handling, (without gimmick) same impact on spectators using the same method.

By the way the method is brilliant if you don't know it yet.
The gimmick idea is also really good.

I understand Max has started shipping thIs item, I can tell you he showed it to me some time back.

You really can't go wrong with this one, the asking price with DVD is very
reasonable.

This is a really clever, practical, and versatile idea. Prepping it yourself will take only a few minutes, and everything looks very innocent and natural.

You can apply ENVELOPE'D to whatever ideas/routines you currently use for secretly switching bills, billets, or other pieces of paper. Max provides you with some good ideas, but the sky is really the limit. This is also a really great tool for use alongside effects that you can create with Max's MBS system.

Kevin

Another fun, clever effect from max. If you have a place for envelopes in your magic, or any routine that requires somebody to hold onto an enclosed packet, I think you'll like this.

Envelope'd is GREAT!!!!
I use this all the time. Highly recommended!!!!