I agree, doing it yourself is fun, but if cost is your main concern, then DIY is absolutely not the way to go. For reference, I recently finished relatively simple ESP32 sensor project and while the components by themselves probably cost about £20, I ended up spending about £150 in parts and tools over the whole process. The extra cost was down to breaking parts and ordering replacements, needing basic components such as resistors and breadboards which many will already have in their toolbox and needing to make about 10 different orders + associated shipping costs as I went through each revision of the design.