I try really hard not to spend any money at all...because once I start I find it hard to stop ("O...well it's only $20 more....." 30 times...ugh).
In the end I usually end up spending $400-500 and owing my friend $150 or so.
Anyway, there's a bunch of stuff
$50 for food
$60 for the train home (we get a ride down, yay freeness!)
$160 for the hotel room
$400 or so for Dealers, and maybe Alley if I end up there
$30 for another bag to haul back all the stuff I bought from the Dealers
$700 total