i just got imovie'11 and was dissapointed that there was not a lot of effects. Is there more but i have to click somewhere? Also can '11 use plugins, and if so where is a goow website that i could find some?
You could find a copy of iMovie HD 06, which has some really nice third party plugin support.
These people have some great stuff.
You could check on ebay for copies of final cut express 4, which Apple has just stopped. I just checked and there are a lot of copies around your price range.