Go to Turbosquid and see what 'professional' models can cost. It will either scare you or send you ROFL. You pretty much have to have Vicky to use most of the content out there, although with a little search, you can still find stuff for Posette and Dork (the default P4 male and female. Long stories). Installing her is easy; DAZ sends all of their stuff as an executable, and all you have to do is tell it you are installing to Poser, and where the Poser folder is. However, there are lots of free characters, as well. Sixus1 has a lot of unique creatures, there's Mayadoll and a few others.