You were very lucky to find a half-built example on eBay

, B-man.. Full-Option kits go for crazy money over here. I suppose this is where the demarcation line begins between models for adaptation (Heng Long/Taigen) and those with a pedigree: Tamiya's products. The gap is narrowing with HL's T90, and improved versions of other models, but it looks as if Tamiya's visits to Saumer and elsewhere with a tape measure, have paid off.
The more accurate the 'model is, the less like a 'toy' it becomes. I suspect most members here have a collection of (ever more accurate) Model tanks, rather than 'Toys'... (but on a bad day I suspect that's what the irate partner will deem them... when the latest addition has been surreptitiously sneaked into the house

)
Here's an early build thread
with pictures I've just unearthed in the RCTW archives for 2010, and it makes an interesting reference to a Panzer IV with only
three return rollers:
viewtopic.php?f=22&t=4632
Check it out before the pics disappear into the ether..

..
Suitably intrigued, I found a few pics of late model Ausf. J's with only three return rollers:

- Roller challenged Panzer IV ausf J

- Three roller Panzer

- PzIV economy three roller version
- Pz IV ausf J three roller version.jpg (13.8 KiB) Viewed 5258 times
Sooo...if you're short of return rollers, this is the version to build

It also makes for a neater, less controversial line up

"Get your facts first, and then you can distort them as much as you please"- Mark Twain.