There are many variables. Do you want a traditional straight, or one that has replaceable blades? Do you want traditional folding or Japanese style that are more like knives; non-folding. What your barber gave you should at least tell you if it's something you want to do. If you do, here are two places to get anything you need:
www.westcoastshaving.com
www.straightrazordesigns.com
And, badger and blade usually has inexpensive shave ready straights in the for sale area- well worth joining if you are serious about this way of life.