Veneered plywood is one option, but if you want to make a tabletop out of solid hardwood while saving money, gluing together smaller pieces can be a very easy and visually appealing way of getting your tabletop.
Here, I am working with cherry turning stock.
I made this tabletop, from start to finish, at Techshop in San Francisco. Great place!
Visit their website at: http://techshop.ws/
Step 1: Cut the Rough Stock
Keep track of which planks were cut next to which. This way you can match the patterns for a "bookmatched" effect on the tabletop.
Step 2: Planing and Jointing
Then, using the planer, plane the height of each plank down to how thick you want your table to be. Leave about an 1/8" for sanding.
Step 3: Last Cut on the Tablesaw
Step 4: Glueup
Have a wet paper towel on hand to wipe off the excess glue once you're done gluing up.
To glue the tabletop together, use wood glue. Get a cup and a brush, and brush every meeting face with glue. Then clamp it up!
Step 5: Final Prep Before Shaping
Using a scraper, scrape all the excess glue off of the tabletop. This should be easy.
Next, use scrapers and sanders to set the surface level and smooth.
Step 6: Final Shaping
This was a very cheap way to create a solid cherry tabletop. Good luck making yours!