I got three folding tables - plastic tops, folding metal legs. I went for 4x2ft tables, as we can play boardgames or skirmishes on one, bigger games on 4x4 using two, and 6x4 games using all three. I can just fit three tables and some gamers into my gaming room

When they're not in use, they fold away very neatly against a wall, as the three stacked together are 2x2ft and only 1ft deep. So I get the room back to use as my office. As zemjw says, they take a ridiculous amount of weight.
Can use them for painting and building scenery as well, or take them to local clubs in the boot of the car. Very flexible.
I went through eBay for mine.
Top tip - buy everything you need in one go, as not all tables are precisely the same height. You may not be able to get them from the same supplier later on, or they may have batches from a different producer.