What's your budget? There's a few GE SA refractors for around $20 + shipping. Could try making an offer since you're looking for 4.
Collect vintage incandescent and fluorescent fixtures. Also like HID lighting and streetlights.
If you can find a cheaper source let me know! Lol NEMA refractors are harder to find now with popularity of LED I guess.Econolight sells NEMA refractors too but they would actually cost more than those GEs and aren’t as nice.