A dress can be rented or borrowed. You could also find cheap alternatives at department stores like
Target wedding gowns
Lots of cities also have second-hand stores or place like ebay will have them. Personally, I found a dress I liked in a shop ($630) but I got it at netbride.com for $371. Sometimes you can also get a nice bridesmaid dress in white for a better price.
Suits can also be borrowed (Mens Warehouse, AfterHours, etc) or bought at department stores.
Really, you could each wear anything you want-- a friend of mine got married in a leopard print dress in Vegas.
Rings can easily be bought as jewelry stores, on-line, even department stores. We found a deal the weekend before Valentines Day... my band cost around $300 but his was free! A cousin of mine got her's at JCPenny. Some stores have the simpliest of bands for $50 and up.
For a reception, lots things are possible. You could have a dessert buffet where only sweets and drinks are served. You could wait and have a brunch the following morning.
Just relax and have fun with it!
