I don't know where you're planning on doing your walk, but the Melbourne one is $15 for adults, and $10 for concession. And you get a sticker with your number on it to put on the front of your shirt, so your OH would prolly stand out without one Also, I believe its cheaper entry at the moment, and will go up a little on the day and closer too.
I think they're prolly including everything in the entry price so they dont have to have all the extra "staff" on, coz they'd have to police everything and be checking everyone before they could enter this, or get lunch etc.
But I know how it feels to be tight on money. Sometimes you just don't have money to spend. Maybe give it a miss this year and attend next year once you have a job and are a little more flush?