There are world class turntables based on idler arm, sprung, and unsprung. Personally, unless one is strongly rewarded by nostalgia for a youthful experience or reproducing a “sound” from your history, it makes no sense to buy old tables. The formula has not been lost. But the available tooling and parts as well as designs have leaped forward over the last fifty years. Especially around the turn of the century there was a huge advancement in turntables.
I would recommend taking advantage of new technology. The Tri-Planar is a very well respected tone arm… I would recommend using it on a contemporary turntable. Go listen to some high end tables.