I have been there before, so I think my comment is not off-topic:
I don't think it is possible to achieve a bass sound with a guitar, which is enjoyable even for just demo tracks.
In my opinion the best solution is to get a Squier Vintage Modified Jazz Bass, which costs about 290 Euros (new).
Until January 15th you can get it at Thomann as a bargain for 260 Euros: