Right now we have a small credenza with glass doors in our condo...anything with store your stuff in can start you off...and if you are looking for a traditional bar to sit at...great bargain places like ikea are a good place to start...but use your imagination and really any piece of furniture can be transformed.
Well...you might not get everything you need perfect right away...I have been working on and adding to my bar for years...start with the bare essentials...
a few wine glasses, beer or pint glasses and depending on what you think you will be preparing maybe some martini or shot glasses.
Bottle openers, wine stoppers and things like that usually can be bought in kits, so look for good deals. Cocktail napkins are always good, along with coasters too.
Then when you are ready to go all out...we even have a wine chiller and a wine rack that we love! Then don't forget to stock it with your favorite liqueurs, mixers and such...and an ice bucket and you are ready to go!
good luck and have fun!
and drink responsibly, take your friends keys and offer then a pillow... :)