How much is a bmx chrome rim?

you can get rims for roughly between $25-$80. some are listed as"chrome", other as "silver". In reality you probably don't want real chrome, as it's too hard and slick to work well with rim brakes.

Do note that rims vary a bit in internal dimensions, and it's no guarantee that you'll be able to reuse your old spokes. Odds are that unless your current hub is really nice it'd be cheaper for you to get a whole new wheel instead of having the rim replaced.