I'm working on an app that allows the single purchase of stickers, not just sticker packs. This means we need to user a credit system for the sticker purchase since you can't have in app purchases that are lower than $0.99. The client thinks it's a good idea to have a status bar always displaying the number of credits available. I think we shouldn't always display to the user how much they're "spending", and that this will make them use credits freely, without thought. I can't find any research on the subject, so i'm wondering if anyone has any links to research of has an opinion for/against? Cheers!
I tried to do a little research for you as well, but didn't come across anything definite. However, after looking at a number of other apps for phones where purchases are made it seems that they tend to have a separate page where you can check your current "credits" and purchase more if needed. This might prove sufficient for both you and your client. As you won't see your "spending" on each page but rather only if you navigate to it. So they won't be inclined to spend less based on what they are seeing from the "status bar" that the client wanted. Just an idea, hope it helps.
I think you can look at anything in the Envato ecosystem for the best practice on this. Not having enough credits isn't going to stop a user from buying something they want, so I actually think you're approaching conversion from the wrong end.
The goal isn't to trick the user into spending more money, it's to convince them that they should do so in the first place.
Show them their credits, that's normal. Make them easy to add and provide excellent teaser cotnent. The rest should take care of itself.
I would suggest showing the balance. When people purchase an app in the first place they are willing to spend money which should already be an indicator that they will spend again. Keep a credit balance, maybe have the credit be different from the amount of money its worth depending on the purchase price of the lowest priced sticker. The customer will feel like they can afford the cheapest so its worthwhile and then splurge if they want better. Easy Peezy!