Guitar Pedal X - GPX Blog - Vox's Valvenergy NuTube Mystic Edge AC30 style and Copperhead Drive JCM800 style Overdrive / Preamps are fairly decent budget options for those genres
Best Buy: VOX Ice 9 Overdrive Pedal White/Blue JSOD
Vox Silk Drive Overdrive Pedal with NuTube | Sweetwater