so basically I should buy one lens at at time and buy all L lenses?
Not at all Photolistic. If you just hung around messageboards all day discussing what the worlds best lenses were and pixel peeped rather than looking at real world results, then you'd have the right idea.
You can get ALOT of value and cover alot of kit with $1500 to spend. If you're primarilly concerned with results you should be fine. There's alot of non-L Canon lenses and third party lenses that deliver the bulk of performance at a fraction of the cost of their L counterparts. That's not to say that you shouldn't buy L lenses, I have one and plan on adding a 2nd very soon.
It's about what will meet your needs at a budget you can afford. Perhaps getting good consistent performing lenses to cover all your subjects/focal lengths at once would suit you best, but would you be happy with that in the long term? Would you be happier getting one lens at a time but getting the best you possibly can for each application?
Some suggestions...
Portrait - 50mm 1.8, 50mm 1.4, or 85mm 1.8 are all terrific portrait lenses that won't break the bank. A fast aperture medium zoom lens could work too such as the Tamron 28-75 or the Sigma 17-70 DC (I've seen some nice portraits done with this lens)
Macro - I have the 100 F/2.8 Macro and love it, the EF-S 60mm is another good Canon alternative. Sigma makes a 105 F/2.8 EX macro that is optically stellar and cheaper than the Canon.
Zoom - I'll just assume you're looking for a long zoom, what kind of subjects/range are you looking for? For wildlife the Tokina 80-400 delivers alot of value and has been talked about here recently. I have a Sigma 70-300 that is really quite good for the money I spent (I'm upgrading my telephoto soon though). My top three choices for non-bank-breaking zooms would be: Sigma 70-200 F/2.8 (if you need the speed), Canon 70-300 IS (you mentioned wanting IS), or the 70-200 F/4 L.




