There are definitely a number of 1/700 kits of the I-400 and other Japanese WW2 subs out there - I know Aoshima and Skywave produce one.<br>
In larger scales, I don't think there's anything in current production - apart from maybe resin kits - but Aurora produced a kit of a Japanese aircraft-carrying submarine (not sure which one, could be the I-400) in about 1/320 scale (close enough to 1/350); this is long out of production and quite rare now.
Nichimo produced a kit of the I-19 (a standard fleet sub) in 1/200 scale; this isn't so hard to find, I've seen a few on eBay UK which usually go for about £20-30. If you live in Japan it may be easier to find (I know quite a few of the Nichimo kits are still available at retail in Japan)