Depends what you consider cheap.
Person A might get a frag that traditionally costs say 100 for 75 and call that cheap since it is cheaper than normal.
Person B might refuse to pay anything over 5 or 10 for a frag no matter what it is calling anything over 10 a rip off.
What exactly are you looking for?
Xenia and GSP which are very cheap.
Or High End Stuff that is Cheap (But not giving it away for almost nothing cheap like xenia)?
Best thing is to get stuff locally (Frag Swap, LFS, etc.) then Shipping is Free.
Personally I find the Best deals in Classifieds by going to peoples houses (Especially Tank Teardowns) But be weary as a lot of Tank Teardowns I went to were very cheap yes but a lot of stuff died because they people often are neglecting their tanks since they know they will not have anything much longer (I find this very immoral since you are both neglecting animals care and selling poor quality animals to others).
I know it sucks and you are probably mad you are taking the tank down but to the very end take care of your animals please.
It is not fair to the animals or to the people that will be taking care of the animals after you.