It depends on the wheel. Bead locks can be heavier or lighter. Most are slightly heavier. This is normally due to the extra strength you need for racing.
My Method bead locks (35#) were heavier then my current Fuel fake bead locks (22#). Both are forged rims. My Walker Evens (cast rim) were stupid heavy (50#). Their the heaviest beadlock on the market ( as far as I know) and ridiculously strong .
Raceline forged are 35# and $850. Their cast is 44# and $450.
Most steel beadlocks run in the 35#-40# range and run around $300 . Personally, I have never seen a steel rim hold up to abuse and will never run them.
The 22# Fuel rim's I currently run will never be abused. If I was going to beat on it like my older vehicles, it would defiantly have real beadlocks.
When you look at rims, look at forged vs cast. Cast will normally be heavier. Forged can be lighter but the lighter you go, the more money they cost. Off road, our tires are heavy as it is, unless you tune your suspension and race, You most likely will never notice the difference.