The ones that
@Michael is referring to are called SSHD meaning"Solid State Hybrid Drive" and I looked into those myself not long ago. They are part spinning hard drive with a large SSD like buffer/cache that can help load things quicker as it can keep some information stored and make it easily accessed.
The thing with them is that the performance is better than a traditional spinning hard drive but not as good as a true SSD. The thing is that you can get a lot more storage space with these for a price that is cheaper than an SSD.
They are a good option if you want a lot of space and a little better performance than a traditional hard drive but don't want to spend the price to get a large SSD.
There are some good ones out there and if I remember correctly Seagate has some real good ones at good price. You might want to check them out a little more.