I have both the Vamo V2 and the Sigelei Zmax V5. Both have VV/VW as well as avg and RMS power delivery. Both hit consistently and I like them. The Vamo is ~$30 or so from
fasttech and the Sig runs $60-70 but is MUCH better built. They both use an 18650 battery (~$10) which requires a special charger (~$10-$25). I have the Nitcore/Sysmax intellicharger i4 and it works very well with all the protection that you need when dealing with Lithium ion
batteries.
All told you're probably looking at about $60-$120 depending on what you get.