Lower End Macro Lens for 1000D/500D?

Hi all,

Have a 1000D and getting a 500D soon.

Can anyone suggest a macro lens suitable for these cameras? I don't want a top of the range super expensive lens. Of course i don't want absolute crap either.

I've read that there are some lenses that are quite good for macro and portraits. Do these lenses have a macro 'switch' on them or something? If someone could explain, that would be great.

Cheers!