Hi mate a lot of razors are made of brass and plated with other materials like nickel ,gold, rhodium and many other things
If your looking for a new razor I'm no help
A vintage razor
try a gillette super speed or tech there cheap and easy to find
member here will sell or trade them
if you want straight brass a bit hard to find
search online for "gillette safety razors" there is lots of types and I'm sure you will find one that you like and
fits your budget
have fun hope this helps Gillette new vintage brass razor (good shave with this one)
I've been a lurker here for a while but I'll jump in on this because I recently did a lot of hunting for non-zamak razors.
Sadly I'm not aware of any readily available unplated brass razors that aren't (a) vintage or (b) way outside your budget. Apparently there are some made in China (Google for "JDK solid brass razor") which should be cheap enough but I haven't a clue as to how they perform or how you'd get hold of one.
If you're willing to go with plain stainless steel instead of brass then things get easier. I just got the Razorock Gamechanger (0.68 gap which is perfect for me) and that's a beauty, though it cost me £65 which is slightly outside your budget.