whats the best one on a budget?
That is not an attenuator. That is an effect that goes in the effects loop and acts like a master volume knob on an amp. Do you already have a master volume on your amp? You'll be buying a piece of junk. An attenuator is a different piece of equipment that goes between the amp and the speaker. That allows you to get quieter power tube saturation. The master volume is what gets you quiet preamp tube saturation.
Those $10 volume box "attenuators" are junk. You won't get the rich output stage distortion with that. A true attenuator will have some good sized resistors in it to absorb the load generated by cranking the amp.
BTW- re-amping is better than any attenuator.
Edit: ^Mike beat me to it!!!