I suggest buying a countertop. It is much trickier than you think to get good straight and dry wood and glue it together. The pros have good kilns, jointers, planers and clamps, and they use waterproof glue.
Check out this website for countertops that you can use to build a table, as well as full-blown butcher blocks. I have one of their blocks that I bought 20 years ago from a commercial kitchen supply place. I haven't cut my way through the wood yet!