IF you can stretch this to 49 keys, the simple Midiplus AK490 spawns enormous quality and playability for the money. Expect to have to search, though Bax seem able to deliver next week. 5-pin MIDI.
IMS, it spawns a battery compartment, which in case I've used extensively.
Maybe obsolete, the M-Audio Keystation 37 is a bit more spongy in its keys' response, but still quite alright. 5-pin MIDI.
I've recently also bought an Icon iKeyboard 4S (three octaves, not four, so 37 keys), which surprised me positively to the degree I'll go for Icon from here on, despite its higher price point. 5-pin MIDI.
Icon has cheaper models too: the iKeyboard 4 and iKeyboard 4X, which I feel still are impressive for the money. 5-pin MIDI.
Icon make things a bit complicated with the enormous range they offer. They offer three different key sizes (regular, mini and nano), lengths from 25 to 88 keys, and also different levels of being advanced and knobby. If you can, visit a shop and compare them. Be aware that the more knobby models tend to have better keybeds, and sometimes the longer models spawn better keybeds than the shorter ones.
I know zilch about USB and about the disabling you mentioned, so can't help there.