Jay:
Another way to save a few bucks on plugs: very often tackle shops will put unpopular (crappy) colors of otherwise good plugs in their bargain bin. These I snap up fast. Take them home, and with a little spraypaint you can turn them into productive lures.
For example, the Manmbo Minnow (a favorite plug of mine) normally retails for about $6. But you can get the lousy-color bargain bin ones for around $3-$4.