Advertising PTC, Amazon & Knovel

One question.

Нow much money can I (first planetPTC hero !) ask from PTC, Amazon, Budweiser & Knovel (see Mathcad 15 / Tools / Knovel) for such advertising, because I'll wear this shirt and this hat for my lectures on Mathcad, because I'll open a beer, this bottle opener, etc.

But thanks to Dan for the gifts!