It all depends on how much you know about electronics. Building an amp is very different from a guitar pedal. I designed both, they are not even close to the same.
For power amp, you have to deal with chassis and heatsink, the power supply on top of the circuit module. It's not going to be simple or a very short term thing to build one. So it all depends on you how adventurous you are, whether your goal is save money or for the ride. If you want to build one to save money, DON'T, it will cost you a whole lot more to build. Go on ebay and buy a used one is a lot cheaper.
If you are interested in learning and building, I would look at some amp pcb kits. They have Nelson Pass's Aleph, Jean Hiraga amp pcb kits on ebay. Those are quite famous DIY amps. Then you can come here and have your own thread and people can help you. BUT, just remember, it's NOT a one day, nor even one week project. I design and build amps, I am very ano in building, from stuffing pcb to finish test the amp, it's about 2 months( of cause I am not doing it full time, say about 2hrs a day, also my circuit is very big). Of cause you can do it in sloppy way and be a little faster. But still it's a long process, nothing like building a guitar pedal kind of one day thing.
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l2632.R3.TR7.TRC2.A0.H0.Xaleph+.TRS0&_nkw=aleph&_sacat=32852Please note, I have no experience with these kits, just a suggestion.