Here's a tip: when you pay a 100 bucks for 20 effects, you have a crappy sound overall.
Some people pay a 1000 bucks for only one effect (reverb...)

So think about what you want: lots of effects to try them all and then decide what to really buy, or really invest in something you'll keep (a wah wah, a tubescreamer, a whammy pedal etc...)
I've heard that Zooms multieffects are pretty decent for the price.