There is a mini PCI-E (as well as NGFF and Expresscard) solution or every kind of laptop, as long as you are willing to fiddle around with your notebook a bit (hardware wise)

http://www.banggood.com/de/Mini-PCI-E-Version-V8_0-EXP-GDC-B...

Mine is on the way, so for now I cannot comment on the stability of the system, but I expect it to be better and easier to setup than Thunderbolt, because PCI-E is longer on the market. Sure the Thunderbolt solution is a closed one-cable thing which looks way cleaner, but I read reviews from e.g. Asus ROG EGPU users, with unstable systems. I absolutely don't want to bad mouth the Thunderbolt solution, I would love to use it, by my system does not have a port. Also, the TB dock is super expensive.