I agree with you that superchargers are somewhat overpriced. But in the case of the 2.6L Kenne Bell, you get the cai, MAF, injectors, intercooler, BAP, and tune. The kits for the S197s are basically like turbo kits. They come with everything you need. Thats were the added cost comes from.
If paying for labor, it will cost you between $4k-$5K just to do the heads. The CNC ported JDM heads are $2995 if you send yours and $3995 without cores. If you do cams, thats another $2K or so. Basically if you do all the work yourself, heads/cams are going to cost you around $4K or so. Then add in the $ a custom dyno tune, etc and your probably around $5k or so. Spend $600 more and have a KB that will offer way more power potential.
Im not hear to tell you your wrong or anything like that. Just trying to save you some money. Spend $5K or so and have an extra 75 horses or so, or spend $5600 and have an extra 150-200 horses with alot more possible with a built shortblock and a pulley change. Hope this post helps.