I, just today as it happens, replaced the battery in my ROG GL752VW (DH-71, but that shouldn't matter) laptop. I had a bit of trouble finding a replacement too. The picture below is an image of my original battery. The new battery I bought appears identical to me.

I bought a "15V A41N1501 A41LK9H battery for ASUS ROG GL752VW G752VW N552V N552VX" off of eBay for about 60 US dollars (as that is the only place I could find reputable sellers at the time). I see there are currently a few results on Amazon now as well for around the same price. It seems to last about 2 hours at moderate to high performance, going up to about 3 hours with decreased screen brightness.
It was fairly easy to install yourself, but you need to make sure that you aren't voiding any warranties. Replace it yourself at your peril, though. You need to largely disassemble your computer to access the battery which is inherently dangerous to the safety of your computer if you do not know what you are doing. There are disassembly guides on Youtube.