I just came from a vehicle with gas struts and I'm actually glad to have the manual prop. The problem with the struts is that they eventually fail and can't keep the hood up. I've seen it too many times. On my last vehicle I ended up using a watering wand (30" bar with a shower head on the end) to prop the hood open. If you really do want them, I'm sure that there are aftermarket ones available. I would check Pep Boys or the like.
I prefer the manual bar because on occasion I need to put the hood up farther than the point at which the manual bar holds it up. To dig around in the back of the engine compartment for example. Having the struts would severely hamper this flexibility unless you disconnected the struts each time you wanted to do this.