L3 is of no value to the type of workload such setups would do. And old Athlons and Phenoms can be had in some places, that is more dependent on where you live and how spoiled the people are there.
Same as I said above... where I'm from with a 750K and a HD6450 overtake the 4300 alone in...
Anything below 6300 is a waste of money. The Athlon 750K goes for around $80, same uArch less the cache, FM2's are cheaper than AM3+'s, almost same performace for less money. If you want AM3+ then the 8300 is the way to go, otherwise FM2.