your better off trying to get a machine on freecycle in your area,or at a garage sale.
i would not bother with a battery operated machine. i bought one for my friends kid..and it was junk.
if you could afford to buy a machine for travel, get a janome "sewest- 509. They run between $99- $169" .
or look for a machine at walmart.
i take my sewing mchine with me whenever i go camping!