Vibration/Tumping - 2007 Ford Edge

I have a 2007 Ford Edge with 110K miles on it. Over the last few weeks the car has started to vibrate while starting from a stop to about 15 mph. Also, once the car is heated up and I drive over 60 mph, if I go around a curve in the road or a large bump (ove bridges, pot holes, etc.) I hear and feel a lound thumping noise and have to pull over, wait a couple of minutes and start out again before it goes away. The thumping is so loud and strond that it feels like something is going to come through the floor of the vehicle. At first this happened once every couple of weeks. Now it happens alomst every day. Talking with a few people we started to think we might wat to replace the u-joints, which are probaby $20 a piece. We now found out that for the Ford Edge you cannot just replace the u-joints, you have to by the whole set up under there which is $800+. Does anyone know if that could really be the problem of if there is anything cheaper that we should try first? THANK YOU!