You are not going to find a professional camera for under $5,000.
There are one or two entry level DSLR's for under $500 with lens, but you will have to search for them. Try Amazon, since they have about the lowest prices for any given cameras.
The Nikon D40 can be found with lens for $450, however look for ones made by Canon, Pentax and Sony.
If you have looked at what the paparazzi use, you will see that nothing they use is close to $500.
I have a former colleague in L. A. that shoots celebrities. He uses two Nikon D3's ($5,000 each) and a 70-200 mm f/2.8 ($1,950) and 400 mm f/2.8 ($8,700) and has two SB900 flash units ($460 each)