Check Craigslist. Any giant or trek mountain bike under $100 is going to be fine and resellable. (make sure it's tuned). The giant Sedona comfort hybrid is especially good if you find one cheap.
A decent LBS might have some used/sale or whatnots around.
Don't bother with locking bike bags. just get a basket pannier (the folding grocery bag types) and a shoulderbag that fits in it.... or get one of the pannier bags that comes with a shoulder strap and take it with you....