I just bought a Sigelei #8 from Hoosiervapors for I think $33. It is not a telescope but does have the side fire button. It's heavy, very solid feeling, and the build quality over all is excellent including replaceable button assembly, negative and positive pins (everything screws in/out). I've already "modded" mine by sanding down the negative center post and button pin to reveal brass, trimmed down a brass screw to fit inside the negative spring and applied a conductive grease on all the threads everywhere, including the button assembly. I still get the occasional weak fire which suggests that I still have more work to do on the button assembly. Other than that it's a great mod and even my vamo is sitting un-used now.
Waiting for my Sigelei #19 which should be in my hands by next weekend. I'm not sure if I'll like a bottom fire button or not but using opposing magnets in the switch in place of a spring was just too intriguing to pass up