Do a search for "4Runner bikini." There are write ups on how to make one. They are a $50 Bestop Jeep bikini and aluminum rail (<$10) from Home Depot plus a snap kit for about $16.
That's how I did it. The Bestop top and front mount kit are under $100. Then all you need is a few pieces of EMT from the Home Depot for a center support and some angle stock to adapt the mounting kit.