5K sale/revenue part time? possible....5K net profit part time while working 100 hrs per week? Yeah right and here is why:
Let do some math, shall we? <let say this guy is working 7 days a week and sleep about 5 hrs a day>
168 hrs per week - 100 hrs at work = 68 hrs
68 hrs - (7days*5hrs of sleep/day) = 33 hrs
33hrs/7days = 4.71 hrs a day to do everything else in his life, including his ebay business (buy,listing, take picture, description,shipping, etc.), then showering, eating, commuting to work, and everything else.
Edit: I hope the OP and his friend are getting pay enough. They are working 2.5 times the normal work hours and if they don't get pay 2.5 times the average/median salary <45K/year IIRC>, then they are getting screw.