I don't think you can get IP camera with 24ch for that budget. And also you might flood your own network if you do so.
What I recommend is:
8ch DVR card x 3 which total up to 24CH - $1000 to $1800
An above average PC which to be sure got 3 x PCI slots - less than $1000
Standard Dome camera - $80 to $90 per piece
Cables - $1 to $1.50 per meter
Roughly makes up to more or less $4000.
Cheers!