The badges made me think of general infos that could be shown in the profile, just dumping some thoughts here:
Profile Info
items sold
customers sold to
countries sold to
reviews (already there)
€ earned in total (would be interesting to find out if sellers are comfortable with that)
average response rate (h/days)
average duration for fulfilled order (days/weeks)
This information could then feed into the badges:
Super seller (=most items sold?)
Friendly seller (=best reviews)
Fast seller (= quick response/or quick fulfilled order)
