I am looking at getting a portable fish finder, because at least for the short term I am going to be renting boats. Long term I hope to buy something and that point my portable will probably become a permanent. So I am looking at something decent but not over the top.

Portable models I have found in OZ include
Humminbird 343CX Fishfinder Portable
Humminbird 383CX GPS Chartplotter/FF Portable (US price is fine, the OZ one is silly)
Humminbird Piranha MAX 210 Portable
Humminbird 535 Portable Fishfinder
Garmin FF90 Portable
Eagle Cuda 168 Portable
HawkEye FF3355P-I
Hondex HE-6100 (but I don't think it will work with tinnies)
plus the junky ones on ebay for $50.

I believe the Eagle FishMark 320 and 480 both have portable options as well. But haven't found anything in Australia about the portable options. I actually believe most of the lower end Garmin models come in a portable version, at least in the US. But I noticed a number of the low end Garmin models mention being for freshwater mainly.

I'd love to work out a way to make a Furuno LS4100 portable, but I don't think its likely. In which case I think I'd prefer a Lowerance or Eagle.

But Does anyone have experience of any of these products (or other "portable" options I haven't found ?

Which brings me to a second question.
Fish finders, in particular Humminbird ones are twice the price (or more) here that the are in the US. Not to mention the concept of a "portable" fish finder is much more readily accepted in the US.

Other then possible warranty dramas, what are the "gotchas" with buying a fish finder from the US ?