It also depends on what experience you've already got. If you know how to solder, read schematics, do a little design work, and troubleshoot electronic circuitry, there are lots of circuits on this site and all over the web.
If you cannot do any of above, get somebody to teach you how to solder and go for a simple kit of some kind.
I would guess you're past this stage. It's still convenient to buy a PCB instead of building your own or handwiring. he ESP site JBL mentioned sells PCBs for most power amps. I have ordered some and they look good.
I would suggest not going for the ultimate in high fidelity as a first project. Layout and quality of construction is a very important part of sound quality.