If your local hardware outlets have a good stock of individual parts, that's how I would do it. In a kit you're liable to end up with some pieces you'll never use and not nearly enough of piece "x".

Most places that stock these materials also have free booklets from the manufacturers that help you plan out a system, do the math for total volume on a line, etc. If they don't, you might be able to download similar from a company website.

You could try Lee Valley Tools.
I have just purchased a load of bits and pieces from them, they do ship out to both Canada and the US.

Here is a link that might be useful: Lee Valley Tools

Local sources will definitely save you money, the shipping if nothing else, and both HD and Lowe's carry the basic supplies.

Online there are any number of suppliers for both kits and the individual components. dripworks.com, dripdepot.com, growersupply.com, just to name a few.

I'd encourage you to look into using drip tape instead however as it is less prone to problems - clogging, spacing issues, GPH emitter sizes for different plants, etc. Plus it generally tends to be cheaper. There have been recent discussions here about such systems the search will pull up for you.

I have about 150 - 200 feet of row

That is going to be your primary problem. No system will maintain pressure over that long a run without inline pressure boost pumps. You'll have to divide it into separate zones.

Dave

My understanding is 1/2" line at 25-30 psi can do 200 ft, and that is the recommend maximum.

Never run more than 30' of 1/4" from the 1/2"

Never run 1/4" porous tubing more than 15'