There are a lot of hardwood lumber dealers in Michigan.Some of which sell various ply's.
You might try a google search.
I owned a custom furniture and cabinet shop for many years and have never seen or had a call for Italian poplar ply.
Could you tell me what's special about it?
High strength to weight ratio. my Buzz Feiten cabs are made out of it, and they are the lightest cab i've ever used. I believe Ampeg is using it for their high end line of bass speaker cabs, again to reduce weight.
Thought i'd slap together some cabs for myself, try out some ideas. The BF's are great, but expensive.
I had to think about it for a while but it hit me that I had actually used it years ago and did know what it was.I used it for some bent cabinet sides.
I used to buy all my ply from a Amish dealer about 20 miles from here.thye sold about any kind of hardwood plywood you could imagine .
I'm going out of town right now, but will get on this next week. A search online turned up on or two CA dealers.... apparently the thinner dimensions are use for bending , etc.. The 3/4 stuff has about 13 plys!