There are some other links here that tell more, but this is what I have heard.
1. Cheap! A par of saw horses or similar, 1 30" hollow core door and 2 2'x4' acoustical ceiling tiles make a great table. The door is light and straight. The tiles are for sticking pins and knives into to hold stuff.
2. Home Depot and Lowes have the cafeteria style tables that fold up, except now they are plastic and around $45.00. That plus 2 ceiling tiles and your set. Walmart actually has one that folds in half too for $50.00, though I have not tested how staight it is yet. You don't need ceiling tiles, but if you are building, they are cheaper to replace than a table.
3. Really Cheap!!! Wait for "big" trash day and get one of your parents to drive you around and look for a big desk someone is throwing away. Maybe a relative already has one, or an office someone works at.
Good to hear you are starting now. Good luck and God bless.