Define expensive?
I did my other one and it had weatherpac connectors ( those are expensive ) for under 30 bucks .
You could do a possibly under 20 if you have any stuff laying around.
Relays are only 2 bucks a piece. Plugs for a ford are under a buck. Wire is cheap, Connectors are cheap.
All of it is cheap if you don't go to an auto parts store.

The one you got probably was short because they sent you a generic size for a car. Just a guess.

 

Cheap relays are part of why my Chines harness failed, they collected water, which was amazing, where I had them was behind the battery under the cowl, battery was dry, relays were full of water, heavily corroded.
I went to a lot of trouble to lengthen what I have, just have been avoiding reinstall or buying another till I can answer why the hell it doesn't work, I tried several different relays, even checked the wire with an ohm meter, lights won't work hooked to it.

 

expensive sealed relays are maybe 5-6 bucks

 

I got 4 right now, I had to replace my headlamp switch, 40 years and it was failing to light the dash, corrosion in it, wondering if it could have been responsible, yet can't understand why the lights worked straight up, maddening.
I made up one for my PIAA rally lights, due to different ends, I can't switch them, but as I said, everything checks out testing for shorts with my volt meter.

 

Well, maybe the switch iS bad ? I wish I was there to troubleshoot it.

You sure have a lot of corrosion issues.

 

The switch was 40 years old, the relays for some reason attracted water to them, they came with the harness, had clear tops, that weren't sealed, they came off, were junk, but there is no explanation why it didn't work when I changed out the relays, the wiring was fine, even had good grounds by the grill.