There are a wide range of LEGO Robotics kits available on Amazon. Components, and complete kits can also be purchased online from Lego. If you wish to view the physical products before purchase then a specialized toy shop, such as Hamley's in London's Regent Street would be the place to head for.
Lego building kits can be purchased from online retailers such as Lego Official store, Toys 'R' Us, Amazon, Overstock, eBay, Fat Brain Toys, Target, and Brick Zone.
Steel building kits can be purchased from construction supplier companies. These kits are used to construct buildings and building frames out of steel.
Lego truck kits can be purchased at a large variety of toy stores. Target, Toys R Us, Wal-Mart, and Amazon all carry truck kits by Lego. Available kits include fire truck, city flatbed truck, city loader, and city garbage truck.
Model building kits can be purchased from modelling or hobby shops such as 'ehobbies', 'Modelaces' or from games shops such as 'Games workshop' or 'Gamleys'.
Researching to find where one can obtain toy robotic kits for kids has provided a range of options. These can be purchased online at Overstock, Amazon and Ebay. These can also be purchased at a LEGO shop.
At a hobby shop, you can find various robotics kits suitable for children. Personally, I recommend the VEX robotics kit if you think the children may be serious about robotics. It is more expensive, but the kit comes with almost everything you'll need for the entire robotics experience from building to programming.
In Indianapolis, there is an Absolute Steel Design and Price center that produces and sells metal building kits. They have several locations in and around Indianapolis.
Depending on your budget and the interest level of the participants, I would recommend the Lego Mindstorms NXT kits, or VEX Robotics kit. Lego provides a user friendly drag and drop programming interface that's simple enough for most 10-15 year olds to figure out, and the familiarity that middle schoolers have with Legos, while VEX allows more robust platforms to be developed, and provides more capable means of building and experimenting with designs. For a middle school though, I would definitely recommend the Lego Mindstorms NXT system, hands down.
Robotics kits can be purchased from local electronics stores. Some other places to purchase robotics kits include Amazon, Toys 'R' Us, Walmart, Best Buy, eBay, RobotShop, and many others.
Lego kits are kits of Legos that come with instructions so you can build things out of them. They usually come with step-by-step info so it can be built. The Legos come in packets.
Metal building kits can be purchased in a number of different locations. There is a website called metalbuildings.com that is one option. Another would be the local big box hardware store like Lowes or Home Depot.
There are many companies and websites that offer Thomas the Tank Engine LEGO kits. Some of these websites that offer the LEGO kits are Amazon and eBay.