Tips on planning a cheap wedding??

My parents are giving us 5,000 to have the wedding. We're going to have it at the chapel on the campus where we both graduated college from, but as far as the reception goes, i'm completely clueless. I'll be wearing the dress my mom and grandmother wore, but change it a little because its very 80's, so i'm only anticipating paying for alterations to rework the dress. its going to be for around 120 people, and the reception can be kind of casual, extra formal isn't our style. we're not too concerned with a cake or anything either. a sheet cake will suffice lol. i would say the most important things that we want to spend money on are photography, some (not a lot) flowers, and the reception. any tips would help =)