I can tell you with first hand knowledge that these are legitimate Motorola GP380 Radios. The companies on Ebay (most from Hong Kong) are fairly legit, of course, how they obtain their merchandise is unknown. For all we know, these can be from a huge batch of rejected radios (mislabeled, failed contract, incorrectly spec'd, I don't know) so they are being sold like a second hand store would sell used or "rejected" merchandise. Or it can be an electronics chop shop. Either way, they have been operating for quite some time with lots of sales so Interpol hasn't come down on them yet.
As for the Motorola GP380, they seem to have the descriptions mislabeled and misinformed on the features; it is often crossed with the Motorola GP338 (but the physical radio does say GP380). Sometimes, if they are selling a GP338, they'll have the info for the GP380. The manual that I have seen was actually for a GP338 but had a white sticker label for the GP380. The radios are typically sold with a RIBless cable and a copy of the CPS which is awful and is an export version but it appears to work very well. All of the features listed on Motorola's site for the actual GP380 are in this radio and it is fully capable.
Should you choose to purchase one of these radios, don't expect to use the power adapter for the charger right away. Make sure it is a 60Hz power adapter first. If not, take a trip down to Radio Shack and get you an adapter and matching connector.
If you want more details, PM me.