For reference, I purchased one of the Chinese second-party "original" warp chargers for the Oneplus 7 pro (specifically, this one: https://www.ebay.com/itm/Official-On...72.m2749.l2649
). The Ebay one was $26.99 with taxes/shipping. By comparison, through the OnePlus website, a warp charger brick by itself is $29.99, and then a 100cm warp cable is $19.99 and a 150cm warp cable is $24.99. Plus, if your order is under $100, another $6.99 for standard shipping or $9.99 for express shipping.
I also purchased a device that plugs into the wall outlet and measures the wattage being drawn from the outlet by a plugged in device. With the warp charger that came in the box with my OP7P, at 20% battery, the measurement would show that it was pulling 36 watts for a couple of minutes. Once it got to the 35%~ charged area, it would drop down to 27 watts, then at the 40-50% area, it would drop down to 22.5 watts until about 80%, when it would drop to 17 watts.
I also tested the Ebay second-party OP7P warp charger I bought through that link. My guess is that all of the ebay sellers and the options from AliExpress are coming from the same, or similar place. With the second party warp charger, at 20% battery, the measuring tool would show a max draw of 28 watts. By 35-40% charge, it would drop to 22 watts, and pretty soon after that it would drop to around 17 watts (maybe at 50% or 60%). I ran this test in two separate buildings, with the same results.
I also noticed that the USB-A side of the warp cable that came with the Ebay warp charger didn't fit as smoothly into the warp charging block. However, it did seem to take on most of the heat from the charging as the warp charging block is designed to do.
Since the Ebay one does 80-90% of what the Oneplus warp charger does for half the price, I'm just going to keep it and use it and hope that some better, cheaper and effective alternatives come out in the future.