One thing I like about kits is that a lot of the really time consuming parts are done. Mainly the layout, sourcing of parts, and all the metal and screen work to make the final result look a lot more professional.
When you go all DIY, to really make it comes out nice takes a lot of different talents. The electrical part I find pretty easy, just follow the schematics and load up the board if you buy the board. From schematic is a HUGE undertaking getting the board layouts. Making the board from the layout isn't too bad though, you just need a drill press and the right chemicals.
Then the metal work, that can really be a pain.
Sourcing parts is a battle too. Most of the time, one place doesn't have all you need, etc. Or if you forget or break one part.
For your first piece it is super expensive since you have to buy all the tools you will likely be lucky to break even. Especially if you count your labor time, probably even more expensive.
It is a labor of love for sure.
Cost in parts range from around $300-$1000 depending on transformers, tubes, etc.
Personally I think compressors are especially hard to kit because of the metering and the complexity of the circuits compared to say a pre-amp. Pre-amps are fairly straight forward and almost rudimentary in comparison. A compressor has a similar set-up to a preamp plus all the additional circuitry for the metering, controlling the compression, etc.
I looked into building my own EQ, holy crap it is fairly complicated to do it any better than a traditional graphic EQ or mixer EQ. Especially to get all the features in of a modern outboard EQ. Then you compare to the price of say a 500-series one, or even rack-mount ones, or even ones on good mixers, and DIY becomes cost and labor prohibitive really quick.
