There's a million low gain, blues-voiced overdrive pedals out there. Many of them owe their existence to this iconic pedal. It hasn't changed a lot in thirty years; they're still great. 

Model: Boss BD-2 Blues Driver
Made in: June, 2008 (serial WX16638)
Type: low gain overdrive 
Power: regular 9v supply
Equivalent new street price (approx): $165aud
Mods: none
Accessories: none
Condition notes: used, no major marks, excellent condition