I fully understand budgets, but if you are going to sink 600 dollars into this, then add 300 and the list will include the bike you want (Jamis/bianchi) and will go above the quality but inexpensive price point. If you go cheaper then the wheels would be worrying me. At your weight and abuse level, a cheaper bike will require the wheels to be replaced in a few years of abuse. This bike will last forever (my road bike is 12 years old and still going very strong), put in a few more dollars and get a much better bike.
Or not...
Scott