Better Deal? Lens help please

[Motley99]

Ok here is the issue - I want to upgrade my lenses (well get better ones) that can be prime or macro that have 1.2/1.4 to 2.8. I have been running Canon for years but thier prices are... well lets say pricey. I need to find out from someone who has been in the same boat if purchasing Canon is truely better (that you pay for what you get) or purchase comparable lenses from Sigma at a fraction of the cost that will give me the same effect. I am using my Canon 30-40 D's for wedding work and I do try to get artsy with some of the shots. I know that die hards and reps will tell me one thing but I am looking for subjective personal experiences as well as examples if you got them. Thank you so much for taking the time to read this as well as providing me feedback!