Is there a way to link two (or more) products such that if you purchase something from product group 1 you must also purchase something from product group 2?

I want to sell shirt designs and blank shirts off my website - so if a person buys a design I want to ensure they've bought a shirt to go with it.
The only way I know of would be to have all the possible designs as a dropdown selection box when they purchase a shirt. If I end up with say 500 designs though that's not a feasable solution.

So can you link the purchase of one product to the purchase of another?

Thanks!