When you go from a refractor to a reflector your taking a step up even without increased aperature. You can build your own 10" newtonian pretty cheap. The stand with a clock drive will cost more than the telescope. That would be the best reason to go with a production model.
I've considered building, but after a bit of research I've concluded that building your own really doesn't save much money (granted, there would be a lot of satisfaction in doing it) ... I suppose quality mass-production and economy-of-scale keep the prices of commercial Dobs relatively low.
There's a lot to be said for letting the experts do it, anyway. I'm the kind of handyman who measures thrice, and still has to re-work :(