Define "reasonable cost". You can range from about $400 (maybe cheaper if you're good at scouring for used parts) to north of $5000. To some people, $5000 isn't even a number to blink at as it's a tiny portion of the monthly income, for others it constitutes an unfathomable sum.

I spent just over $1k on bilstein 6112 and 5160 with OME 906 rear springs. That was "reasonable" for me and my budget.

FWIW, if you do Just a plate bumper, you're splitting the fence on spring rates (it'll be a Touch soft on 4runner rates, and a Touch harsh on Tundra rates), add that winch and you want Tundra spring rates. I knew I'd never put a plate bumper on (hate the looks, don't have any functional need), so I went with stock 4runner spring rates front and rear.