I need a dslr camera with hd video and port for external microphone?

But not too expensive.about nikon d5000. Or canon 500d. What do you suggest?

Nikon D5100 or Canon 550D.

You will want to visit a proper camera shop and test each to know which one is best for you.

I own a 500D and it's an excellent camera for both video and stills but no external audio. For that it's the t2i or t3i - more excellent cameras. They run about $800 and $900 respectively with a kit lens.