Thank Archer over on XDA for an easier solution
here
New Simpler Method
Simply copy and paste this code into the address bar when you're on the relevant Google Play page in your Desktop Browser...
Code:
javascript:document.getElementsByClassName("buy-link")[0].setAttribute("data-ispurchased", false)
You could create a bookmark of that if you expect to need it often.
Old Method:
Prerequisites : Desktop/Laptop computer Browser with ability to "inspect element"
Must have a valid credit card and a registered wallet account for this to work
And must be able to follow directions
Thank -
jollyb for Finding/Translating
THIS fix he found on a croatian forum.
1. Open Google play (Market) in Chrome browser (on your desktop/laptop) and find the wanted app (best would be that you backup the app via Ttitanium backup if you can, and uninstall it)
2. 'Right-Click' on "PURCHASED and select Inspect element
3. Above the selected row you'll see [data-ispurchased="true"]
4. Change "true" to "false" and press ENTER
(Having problems with downloading another app? Change the inspect element back to "true", app should start downloading now)
5. Click PURCHASED that will open the popup to buy via Google Wallet so you can purchase the app.
Tested on Google Chrome browser, please post if you've had success with/on different browsers.
MoPhoACTV Initiative