OK, I'm coming here because I want to get some advice - there seem to be SO many of these types of pedals out there, it's pretty overwhelming, so maybe I can explain what I have and what I want to see if we can "whittle" some of the choices down.

For an amp, I have a VOX AC30.  It really doesn't overdrive on its' own, and really wasn't made to, and I LOVE the fact that it does what it does.  However, I have it in my studio and I had a client yesterday that wanted a nice natural-sounding overdrive - one that isn't obviously "metal" sounding, like the kind you get with some vintage amps or even maybe a Marshall.
 
All I had to use was a EHX Big Muff, and it really wasn't what my client was looking for.  To "Metal" sounding.  I think we just need slight saturation, a little creamy maybe, with - you know - that "vintage overdriven" amp sound.
 
So, My price range is roughly $100-150, and I'd love to hear recommendations from people here based upon my needs.
 
Something that works well with both single coils and humbucker type guitars too, would be preferable.
 
Thank you!!
Scott

You pretty much described a tube screamer. Nash Pedals have a fantastic tube screamer type pedal. I have a TS-9 Tube screamer which is pretty versatile. I also have a Nash 808 and I like it better. Either way you can't go wrong and both are right at your price point. I also have a Barber Direct Drive which I also love for more modern crunch tones, it's not really a metal pedal either . You may want to take a trip your local music store and audition a few. I hope this helps and Good Luck.
 
Rocky 

http://www.gearslutz.com/board/reviews/884824-mooer-green-drive.html
 
This was what I bought after spending about an hour with a pile of pedals in a store. 
$87 CAN
 

 
http://www.mooeraudio.com/en/Product.asp?PClassID=25
 
http://www.tomleemusic.ca/index.php/163784.html
 

It sounds like a Tube Screamer is what you need.

Well, I went Old Skool and got myself an MXR Distortion +.  I think it's just what the doctor ordered!  My guitarist has an Ibanez Tube Screamer I'm going to try out as well.  Just wanted to add to the arsenal!
 
Thanks everyone!

+1 on the tube screamer.  You can't go wrong with it.  I think a number of guitarists in the 80's paired a tube screamer with a Vox AC30 amp, so that's a good combination to get that classic 80's distorted guitar vibe.

the tube screamer killer
 

after owning original tube screamers AND reissues, i can attest that this machine does it better.
 
i use an older version of this, called a direct drive super sport.
good stuff, go here to see the whole list:
 
http://barberelectronics.com/products.html