i dont know if this is the right place to ask this, but ill go ahead anyway =]

i need something, probably for under about 150 pounds, that'll put effects on my voice, a kind of multi effects pedal but for vocals

the kinda thing im looking for is

distortion, that kinda lo-fi thing you hear on a lot of songs, and other such cool things i can do to make vocals that little bit more exciting

oh and also it'd be great if there was something for imitating a megaphone =]

Seems like an okay place to me...
And I have no idea personally what you would need.

I run vocals through a spring reverb sometimes, that sounds awesome.
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
maby take a guitar pedal and change out some components to make it operate on vocal frequencies...
a small bit of flanger on the vocals often makes it sound real good, and really fitting for some songs.

No Rain, by Blind Melon is a perfect example of that.

Other than that, i dont really know how to get any other good effects on the voice.

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What about a wah pedal. Change the frequency response a bit to suit your voice and away you go. ATM I'm messing around with mixing two or more wahs together on the same pedal to get a vocal sound from my guitar, so doing a similar thing might work for your voice.
A cheaper way, sing through your guitar and use the effect simultaniously
the guy from coheed and cambria did it at leeds last night (i saw it on the TV) and it sounded pretty damn cool
also try a phaser effect, it gives a good sound, led zeppelin uses it on "what is and what should never be" on their album and it sounds incredible.