In my opinion, the best vaping device for concentrates is the itazte SVD by: Innokin.
Every patient that has tried it with me has said hands down it is the best they have ever had period.
My second favorite vaping device is a eGo-C Twist 650 variable voltage cheapie pen battery with iClear 16 Dual Coil Clearomizer. Both of these units, the mouthpiece and heating element are rebuildable. For less than $5 you can replace the wick, heating coil, and such just by unscrewing it and screwing in the new one.
In the picture of the pen vape, the red clearomizer is the one I use for e-cigg oil. I was too lazy to shoot up the picture of the clearomizer that I use for e-cannabis oil. The clearomizer I use for e-cannabis oil is tinted black, great for stealth. There is no reason anyone would think it is anything but an e-cigarette, just with a dark clearomizer attached.
The last picture shows some of the vaporizers and accessories I have been playing around with. I have much more.
I have only worked with RSO. I don't like vaporizing it straight, I feel it degrades it. So I mix it like e-cigarette oils. All I do is mix the RSO with some Propylene Glycol USP to get it to an e-cigg oil consistency. Only use food/medical grade propylene glycol USP. I mix it about 20% PG USP. Anywhere from 10-50% depending upon personal preference.
Both of these vaporizers are dual heating elements, quad wicking, and positive action! BABY!
Edit: The least expensive complete vape kit that works best with e-cigg or e-cannabis oil is the Dream Vapor Electronic Cigarette, $25.99.
The best pen vape in my opinion is the eGo C Twist 650 variable voltage, less than $20 for the battery and the iClear 16 Dual Coil Clearomizer less than $7. The best all around vaporizer is the itazte SVD by Innokin $89, $120-$150 with batteries and charger depending on parts chosen. For quality, I would put the SVD up against any vape on the planet whatsoever. These were purchased from High Desert Vapes.
All three of these vaporizers have the inner 510 threads and the outer eGo threads.