As goofy as it sounds, an oil pan is a very important part of your "complete engine assembly" . . Without a properly designed (and built) pan you are putting all the other high buck parts you've invested in at risk . .
Not to mention, possibly losing 25-35 HP to windage. And, with windage and a lack of storage volume, you may run out of oil at the top end of a run (it's all either in the top of the engine or suspended by windage) . .
And as was mentioned, excessive windage also can break welds inside the pan, further disrupting oil return flows, and unless you get lucky and find the problems on a teardown, you get to re-invest when the oil pan problems manifest themselves!
And waaay back when I was doing a lotta fabrication, I must've built, modified or repaired several dozen "Racing" Oil Pans, and disregarding how much time I had in 'em, they weren't any better than the expensive ones and certainly, more expensive if you got paid for it.
Currently, I'm a crew chief for a guy who owns a sheet metal fab shop, and he could probably build anything we've bought, but when you look at the engineering and time it takes to build a good oil pan, they're really pretty cheap and damned good insurance . .
Back to the "Cheap parts" saying . . Ask yourself, are those T&D rockers or those high Buck Roller Lifters worth saving a hundred or so bucks on an oil pan for . . ?
Jus' sayin'