My experience doing just that...
Bought a Lightbridge 16 a few years ago from Bintel. @$3000 at the time
Didn't like the views, never quite focused properly, heavy as f%#! so I...
Bought a Mark Suchting 16 f4.5 mirror for it $3400 roughly (love it, its a great mirror I'll never sell)
Protostar secondary $300 to $400 with shipping
Feathertouch Focuser again $300 to $400
A few other bibs and bobs, springs, shroud, dew heater, weights ect. mostly from scope stuff.
Rebuilt the base using ply, changed it to allow passage through a standard doorway and added wheelbarrow handles.
Just recently added ServoCat Jr and Argo Navis for goto and tracking. @$1800 all up including shipping, customs and GST.
Its now a pretty good scope and now only needs some svelting.
Would I do it again knowing what I do now.....? Nahh!
I'd save a deposit and pay Peter Read at SDM to build one. By the time it was ready you will have saved enough to pay the rest off.
There's a reason you hardly ever see them up for sale second hand. Invest in quality. My 2cents
