The problem of where to buy is why to scatter the offers.
Best are reliable up and down coins like DeVCoin, it regularly goes down to somewhere in the 55 to 30 satoshis per coin range and up to over 175 or over 200 or even over 300 once upon a time. It went down to 27 once.
So I simply have a buy offer at each and every satoshi of price from 1 satoshi all the way up to the current spread, and sell offers from way up over 200 someplace all the way down to the last place my highest buy offer was sitting.
It makes a nice regular income, and jumps from 30 or less to 200 or more are quite enough profit considering I don't have to screw around with dubious crap coins that aren't even on reputable exchanges.
The problem of where to sell is solved the same way the problem of where to buy is: buy all over the buy side and sell all over the sell side. No matter how far it goes out of the boring mid-range you profit.
Also on Vircurex having bitcoins on the exchange earns you income from the fees the exchange charges, so the more bitcoins you have sitting there in offers the more you earn.
Thus hail-Mary lowball offers that are insanely lowball still earn something even if the price never does go down to 1 satoshi or 2 satoshis or 3 satoshis or whatever.
Since you can save on fees by signing up using a referral URL here is my referral URL:
https://vircurex.com/welcome/index?referral_id=597-1636-MarkM-