Why bump? You have a few good ideas of amps that sound good and are reasonably easy to find parts for & build (but also not so easy to the point where they are totally mindless to build) in the PPA, M3 and minimax. Pick between the 3 and go solder. Odds are good that recommendations to build other amps are not so good.
As another point, DIY'ing to the point of breaking even dollar wise is extremely difficult. If you are on the budget where you would buy something to try and return this may be a factor. food for thought. When you factor in the emotional rewards of building something that dosnt catch on fire the first time you flip the switch money becomes secondary to the deed. If your just looking for something cheap & good surf the FS forums find a good deal on a desirable amp and sell it a few years down the line for pretty much what you payed. I bought a nice commercial amp new and owned it for a bit over a year and sold it for 90% of what I payed. This is not uncommon. With good quality second hand gear it is not uncommon to break even! I have rarely come close to recovering 90% of my parts cost on DIY gear although I do find that gear that borders on "dosnt exist" makes this easier. Designing your own amp, or matching 100's of FETs is a good start.
Something else to note: people who do this for fun build one and build another and build another.... and then the cost REALLY becomes secondary to the many rewards of building your own gear. Very few people build one DIY amp. nip the habit in the bud if you dont want a few amps hanging around in a year. This is actually why its weird to ask what to build, once you start you will probably build all of those anyways. you will make mistakes on the DIY journey, you will blow up some transistors, you might even blow up a tube, you may even build some amps that have your side ache from laughing at how terrible they sound, but thats all part of the DIY journey. Its the amps that come out outstanding and make you say "wow, I built this and its awesome" that make it worthwhile.
sorry.
