Oh no....no no no no no. Are you kidding me? You don't think dropping dough on a good set of plugs is good prioritizing? Holy shit.
Put it this way...do you think the stock/built-in plug-ins for whatever host you use are as good as Waves/MH/URS/etc.? If you answered "no", then dropping coin on a plug-in bundle is WELL worth it. Unless you have good outboard gear (EQ, Comp, Limiter, Verb, etc.) then you definitely need to have SOME kind of processing in the box other than built-in shit. Without processing, all you have is raw tracks. That sounds like shit unless you want that sound...and even then it still sounds like shit. Built-in plugs are "OK" at best...or rather, "good enough until you get Waves", lol. I can't see a reason why anybody shouldn't buy a good bundle of plugs. If you have the money, and yo don't have the plugs...buy them. You won't think they were a bad idea once you start using them and realize why they charge money for them.
As far as which ones...that's up to the user. Some plug-ins, even though they are software, still have their own character, even if it's really transparent. Like hardware processors, software plugs have their own little musical sound they add to the audio they are processing. Some people like how Waves' EQ affects the track, others like the URS eq or UA Neve eq. Same with comps. It's all subjective to the user. Just like guitars and amp, you need to try them out and see what you like or dislike about certain ones.
Thats just what I think anyway.
~e.a
