I wouldn't rule Dtech out based on a crappy website or their posts here. They don't participate on the forum much. My personal experience with them was fine and I won't say anything negative about their service. I think they tried to offer something for our little cars to make them better. Even if some people don't like the product, I can stand behind anyone that's trying to make things better and has a passion for 2002's.
That being said, you defiantly can do this on your own. Your basically buying a kit that has the parts all together. The one advantage to getting your own kit is that you can choose the quality of your setup. Dtech isn't going to send you a Sanden compressor or a Spahl pusher fan. Nor are they going to send you the fancy new compressor bracket that Blunt started offering this year. I think they now offer a compressor bracket but I don't know anything about it and how it fits. It's an important piece to get right and is dependent on the year and style of your block.
Find a local Hose/hydraulic shop to fabricate you low and high pressure hoses etc. Dtech sends those hoses to you without being crimped so your going to go there anyway. If you run those hoses down the inside of the right fender make sure you secure them to the fender. I had a local AC shop recharge my system and one of the hoses fell out of place and sat on the exhaust header. That ends up with a fire in your engine bay. Yep, that really happened to me. Yes, they paid to fix the damage but not a fun experience. @whaldriver ran his thru the fender and then back in. That's a smart setup and makes a little more sense if you don't mind poking some more holes in your car.
Talk with Hurricane to get the right controls knobs etc. That part is unknown to me because I have been on their website etc and I can't find the products that were sent to me. They have them but probably not listed on their website.
Remove your old heater box and go down to your local metal shop and get a block off plate made out of a piece of scrap metal. 1/4 steel is what came in the kit. It didn't fit the hole properly anyway so I had to take it down to get trimmed anyway. This is the nicest part of this upgrade. Bad seals in your engine compartment allow fumes to go inside your car. That problem goes away with this block off plate.
Depending on your setup, choose a good quality pusher fan. Spahl seems to be the go to brand. They aren't the cheapest option. In my car, I had done a fan delete so I went with the biggest thing I could fit in the nose of the car. I believe it was a 700+ cfm fan that cost me about $150. I also purchased their temp control on/off switch. Turns on at 195° and off at 175°. I had a local shop install that switch into my intake manifold. (That = tearing your carb out etc) I had to also wire it to turn on when the ac was on because I didn't have the mechanical fan moving any air when the car was not moving. No air pushing across the condenser = bad AC temps.
This is by far not the only things to consider. I paid to have mine installed and worked out most of these problems after the install wasn't exactly what I wanted. Doing it again, I wouldn't pay someone for the install. It cost me over $2000 just to end up with something that wasn't perfect. I'm a little OCD however.
Anyway, take the info you like and leave the rest behind. Hope it helps someone at some point.