Misty, it wasn’t your imagination. Forbidden Lego does require unique parts such as technic pieces and some of the models require old motors. At age 10, you might want to consider purchasing him a technic “set” first and see how he likes building with technic parts and power functions.
Ok so looking at the Technic. Which ones where your childrens favorites? Best bang for the buck? I think even my 14 yr would like one that has something like a motor as he’s always trying to build a motor out of lego’s that works.
If the model includes power functions, the motions will either be triggered by a switch or remote – otherwise they’re manual hand- cranks. My boys have had many favorites over the years, however the majority of those are no longer in production (LEGO sets are ever changing). Currently the only power function capable models are in the $100-200 range – yikes. However, if you wanted to add power functions to your 14yo’s current Lego collection, there is a “power functions motor and light pack” you can purchase separately http://shop.lego.com/en-US/LEGO-Power-Functions-Motor-Set-8293 .
For your 10 yo I would recommend starting with something like a helicopter or ATV, as these are good introductions to the building concepts. http://shop.lego.com/en-US/TECHNIC-ByTheme
We have done the Lego Robotics and it is a lot of fun! There are a lot of Lego clubs out there. It takes it all to a new, educational level. But, I have to say, that my 14 yr old boys still love their Legos especially the Star Wars Legos. I finally looked at it from a different perspective, what are other boys playing with at that age? Are they even playing anymore? Legos started looking really wonderful to me after that!