I purchased the 24-bit version of LZ 3 from HD tracks. There was a bit more background noise as compared to the boxed-set CD pressings of a few years back, but there was a lot more palpable energy.
Back on Black: LED ZEP 1-3
Available on preorder through Music Direct and Acoustic Sounds. Remastered by Jimmy Page on Atlantic label. The fact they are available packaged with a CD is kind of a red flag for me. Hopefully they are sourced from the best available masters, and there is NO NO NO digital in the chain. Slab weighs 180 grams, $24.99 US!