Yes. With one exception, every kit in our bundles is also sold on its own product page, so you can buy a single item instead of the set.
The exception is the Mars Rover expansion modules, which appear as an Add-ons line on the Mars Exploration Bundle page and have no product page of their own. If the modules are what you are after, check what is already included with the Rover kit before you order the bundle: What is in the NASA Mars Rover box lists the contents of the standalone kit, and What is in the Mars Exploration Bundle, and which part do you build? sets out what the bundle holds.
What you cannot do is change a bundle. Each bundle page sells one fixed contents list as a single product, with no option to remove an item, swap it for another, or add a kit to it. If you already own one of the kits in a bundle, buy the remaining ones from their own pages. We cannot supply a bundle with an item taken out of it.
Bundles are priced as a set rather than as the sum of the kits inside them. Prices and promotions change, so compare the bundle page against the individual product pages at the time you order.
For what each current bundle holds, see What is in each CircuitMess bundle?
If the order is already placed and you want to drop one item from it, see Can I cancel just one item from my order but keep the rest?
If you are not sure which page sells the item you want, message us here, or email [email protected], with the kits you have in mind and we will point you to the right pages.