In reply to Roberttaylor:
Mpb.com is great place to find decent secondhand kit if you haven't already had a look.
The Nikons you mention can all be hacked for 64mb bitrate too I think. I've hacked my old D3200 and it seems to be OK.
The standard 18-55 VR lens from Nikon is still excellent for the price, and if you go for one of the newer P series it has quieter motors which can make a difference if shooting on AF with an on-camera mic. The 35mm 1.8 is also excellent, and about right for filming others (a bit too close for filming yourself handheld though)
Frame rate will also make a difference. If you want more of a film look then you can shoot at 25fps, but if you want to capture some action and slow it down in the edit you will want a higher frame rate - the older Nikons don't offer anything over 30fps at 1080 HD.
Leave something in the budget for spare batteries and maybe one of those camera armour rubber thingies.