The pet and wings add $10 to the cost of the package, and would be roughly equivalent to the goodies found in WoW’s Digital Deluxe versions and associated standalone DE goodie packages.
Here’s how the pricing works:
Standalone D2:R = $39.99
Standalone D3:E = $39.99
Standalone Complete Edition = $89.99
The Complete Edition contains D2:R, D3:E, and the cosmetics. If you do not own any D3 items, it will cost $89.99.
If, like me, you own some or all of the Diablo 3 items, the cost is lowered for the Complete Edition. Since I own everything contained in the D3:E package, I have only two choices on my Shop page: D2:R for $39.99 or the Complete Edition for $49.99. That’s a $10 difference for the cosmetic items.
It makes sense they’re selling it this way as it gives players choice between a “basic” and “deluxe” edition. Since there are only two cosmetics and nothing else with regard to the D3 items, the difference is only $10 as opposed to the standard $20 difference one usually sees with the DE versions.