Is it better to buy a radio telescope as it is for optical telescopes?
Optical telescopes have unquestionably gotten more affordable in recent years, to the point that it may not be worthwhile for you to attempt to construct one on your own.
With just $500, you should be able to get yourself a high-quality optical telescope.
Unfortunately, this is not the case with radio telescopes. The cost of commercial radio telescopes is in the ridiculous column.
You better be ready to spend a fortune if you want to buy one yourself.
That is why DIY radio telescopes are a means of monitoring radio wave activities from space without spending the money to buy one. If you can, and want to make one without breaking the bank, go for it.