Power supply module for TPA3250 or similar

Hello,

this is my first post. I’ve discovered this forum years ago and gained lots of helpful information here. Thank you!

Maybe someone can advise me on this matter:

For education purposes I need mono or stereo amplifier modules that I can customize a bit for my needs.
I've decided to try this with the TPA3250. I've found some inexpensive assembled boards on the internet.
Now I'm looking for a suitable DC power supply, in the range of 18 - 30V and ~ 4A.

I'd prefer using a linear power supply instead of a switching PSU. But I'm also open to recommendations for quality switching PSU.

For me it's more important to keep it not too expensive because it is needed in a medium quantity (8 - 16 pcs.) for experiments with unconventional speaker setups, exciters/shakers, in the context of sound art installations.

Is there anything pre-built based on - for example - the LM338 or something similar? Or can anyone recommend and point out a schematic/layout from an open hardware manufacturer. There is probably already something written here that might help me with me questions.

Thank you very much.