Alpha, I buy according to my needs, however when I do buy these are the usual companies I use and why:
If I am after shemale or quality mature content then I will go to club-xstream. Martin is ultra helpful & if you promote Hawgscash or Lovercash I use my Hawgspoints and get an extra 20% of content thrown in. If you go for high quality milf sets then searching through the pics by Michael Peterson will bring rewards. Also if you are TGP posting then their package sets are exceptional.
If I am after a more amateur housewife look then I go to Skanmedia (norespect.com). It can take forever to sift through their stuff but you really can find some gems in there & you can select single pics.
For teens, which is quite rare for me, I would head over to Paul Markham/Bargain Basement as Pauls stuff is really good plus his girls are hot (usually).
Also in the past Tim from Timifoto has done some great deals and his stuff is top notch. I am not sure if he is still producing for general use, but it might be worth hitting him up on icq to see if he can help you out ~ his stuff really is that good.
I recently used Garill & picked a fews sets up. They seem to cover most niches & again you can select individual pics (and at a standard price). Gabe was very helpful too.
Hope these thoughts help and I am not in any way affiliated with any of them
