The only 1/72 Italian WWI big bomber was done a few years ago by Meikraft, the Caproni Ca.3. I did a lot of the research, instruction sheets and decal decisions. It was expensive then and now, with Meikraft and it's owner deceased, they can fetch a pretty penny, over $100 usually.
Of course if you are only building occasional models try looking at it this way: Buy five $20 models and take five months to build them or one Meikraft Caproni Ca.3 and take six months to build it.:-)
It was predominanently injection molded with several cast metal parts, included rigging material (two of the six months worth of work), wood veneer and superb decals. Have seen them of e-bay fin the $100 range.
The Roden line, which started as Toko, has a very large range of superb 1/72 WWI kits from the Gotha bomber and just released Felixstowe to their wonderful line of fighters.
If you are looking for particular subjects and can't subscribe to ESM 72 (Vol.6, #3 and #4 covered everything ever produced on WWI subjects with updates continuing through Vol.7) just post a request here and I (along with several others) will be happy to help you find them.