my friend did this, he made the setting to his amp to high bass, low treble. see if that works for you. the sound wouldnt be good as a bass amp, but there's still sound.
There'll be sound definitely. 'Cept it'll sound like crap.
And you might bust the guitar amp.
Try Craftsman or J&D. TGM if you're confident of finding a decent piece.
Also can look at SOFT's classifieds. Aria, Samick and whatnot.
It is not recommended to plug a bass into a guitar amp as the frequencies are different, and chances are that it will crack or spoil the speaker drivers of the guitar amp.
Look at the classfieds for some 2nd hand bass amps which can be quite a steal.