You will need a bigger alternator and wiring upgrade if you go with electric fans. Mine was not as budget as yours, but I still use a stock radiator with two Flex-A-Lite Black Magic fans
https://www.summitracing.com/parts/FLX-104310.
I upgraded recently from a 200a CS130 (dead rectifier) to a 250a CS144 from JS Alternators. I have 2ga wire from the alternator to a fuse block, then to the battery. Relays control power to the fan, while a separate fan controller exists inside the cabin for temp and A/C kick on. I highly doubt you'll do this for under $400, but you might be able to find some gently used parts out there.