Lens recommendation for Canon T4i?

Hi, everyone.

I'm still learning to work with my newly purchased Canon T4i but I have noticed that I would like to get a few particular lens and items. The lens is something that I would like to get the more experienced photographer's opinions of.

I'm trying to find the best price/performance point for a budget-minded person like me.

I would like to get...
wide angle lens
good zoom (maybe 500mm or more)
Macro lens

So far the only lens I have found that I'm at least a little confident in is Sigma 150-500mm f/5-6.3 AF APO DG OS HSM Telephoto Zoom Lens at http://amzn.com/B001542X6E .

Is this a good pick?

I'm still open to any better lens for the price and any feedback on my endeavor of this lens search.

In case you are curious about what I already have...
EFS 18-55mm 1:3.5-5.6 IS II
EF 75-300mm 1:4-5.6 III
Vivitar Series 1 70-210mm 1:3.5
MC ROKKOR-PG 50mm 1:1.4
MC auto extension tubes for minolta SLR cameras (14mm, 21mm, &28mm)
Fotodiox Lens Mount Adapter
(2 Nikon lens that is in storage (one is macro) & an adapter for this)

Thank you so much