The question probably shouldn't be "is it less expensive" but "is it a better value".

The general sentiment behind these 3d printed telescopes are that you'd generally get better quality and potentially better QoL features at the same cost of buying some commercially available options.

From the Hadley project

>The mission here is to make an attractive alternative to the shoddy, hard to use "hobby-killer" scopes in the $100-200 range.

It’s not really the telescope you’re printing, but some custom fittings to assemble metal rods into a telescope.

People have been making telescopes with this method before 3D printing existed. They just used something else for all the little dodads.