Atherosclerosis is asymptomatic for decades because the arteries enlarge at all plaque locations, thus there is no effect on blood flow. Even most plaque ruptures do not produce symptoms until enough narrowing or closure of an artery, due to clots, occurs.
Replacement Mirror Glass Cost. If your mirror is scratched, cracked, and needs to be resilvered, then you may opt to hire a service for mirror glass replacement. The cost of the original mirror, its condition, and the extent of the damage to the glass will all help determine your best option. The same costs from above apply here. It will normally cost $10 to$20 per square foot to replace mirror glass.
Dobsonians can certainly give the most aperture for the dollar. An 8 inch Dobsonian, like the Orion SkyQuest XT8 Dobsonian Telescope, can go for under $500, while an 8 inch Cassegrain will generally cost $1500 and up. Of my telescopes, I use most the 6 Inch Newtonian, which has the largest aperture of my instruments. Next used, for it's convenience, is my 60mm Carton Refractor. It can't bring in some of the dimmer targets like my 6 inch, but shows superlative star images, and is exceedingly easy to use.