Hitch Receiver - modest cost alternatives?

My series III frame has holes drilled on the back for attachments (I assume all do...). 4" on center both horizontally and vertically. Want to mount a hitch receiver (2") so I can attach things like cargo trays.

Any inexpensive alternatives to the OEM version that costs hundreds of dollars? Cannot find anything with 4" on center bolt pattern.....

I have one of these - works pretty well but is higher up so you need a drop hitch for a trailer.
https://pangolin4x4.com/item/64