Bintel (or other suppliers ) can sell you the mirror, and the secondary mirror normally comes with it, package deal ! You would also need to buy a focusser but the rest is quite within the scope of a DIY enthusiast. (Actually a very good learning experience I found).
I'd suggest a 10" f5 rather than the 8" f6 because aperture rules and they work out to be very similar in size. The 10" would be only slighly fatter.
My first scope was literally just a pair of wooden boxes, one for the mirror, another for the focusser, 4 alum rods and and a rotating cradle for it to swivel and move in and was just amazing. It has been rebuilt since into a Serrurier configuration, another DIY build.
What tools, working space, materials and experience have you got ?
Unfortunately I'm over the other side of the ditch so can't offer any resources or physical help but along with any others we can do our best to get you started.
My first build took about 4 months btw as I learned and experimented with options so don't be in too much of a rush. Ask questions and you will get answers.
Good luck and

btw