Well, it looks like the verdict is in! Metal posts with clear resin lamps it is! I can offer to sell clear resin posts to anyone who want's them (send me a message if you do), but by the sounds of it, most of you would prefer the metal posts.
I wont be trying the LED lit lamp post. I have thought about it but want to spend my time making more models. I have so many I want to make!
Thanks everyone for your comments, very helpful!

I'm thinking of supplying the lamps with little plain round metal bases and selling them as a set of 4 of each size. So there would be a set of 4 small posts with little lamps, a set of 4 medium posts with little lamps and a set of 4 large posts with large lamps. That's the plan at the moment.
I'll get to work on these soon as I can and I should have a few other bits of Victorian Street furniture soon.
I'll keep you up to date with when they will be for sale and also the cost.
If you have other comments, please let me know!