i was wondering what the standard frequencies are that define the low-mid-high of a (bass)guitar?

if i look at the 7-band eq on my amp it's <250 for the lows, 250-1k for the mids and >1k for the highs. are these a bit right?
Well your low E string on a bass guitar is 40hz, instrument speakers usually cut off almost all the signal past 7khz or so, your mid range usually is somewhere between 400hz and 1khz depending on what amp you have.

Looking at the EMG onboard EQs they've got it set up as 30hz for the bass, 600hz for the mids and 6khz for the treble.
look at the EQ curves there http://www.emgpickups.com/downloads/wiringdiagrams/B30EQ-B64EQ.pdf