Ginzeru

@Lycanth @Fierce Godhand I found a solution, create a user and make it a bot, like a Bot name, bot titles etc
You can configure the plugin to get the bot automatically sending DM's with the voucher to users.
There will be no blank screen anymore.
It's working with me! 
It's a test, but working very nice! If you need help contact me, I will show you my settings!
 

@TheJackal84 I understand what you're saying and I appreciate your feedback and advice, but doesn't the trophies app do something similar? Also the IPB3 version of shop allowed images to show in the inventory. Would you allow me to hire someone (or yourself!) to modify it to do what I'm trying to?
Also, like the above person I get a blank screen after purchase as well.