I kind of get the impression that these people aren't reading the OP in the first place and that a FAQ wouldn't help. There isn't room to add anything else anyway without rewriting and removing some of what's already there.
I mean, the order of display solutions discussed in the OP basically goes: CRT (plus SCART-to-component converter if needed; PVMs mentioned), old monitors and basic linedoublers, and finally HDTVs plus upscalers. So, the major bases are covered, in order from cheapest to most expensive.
It's either that, or these people don't like what they hear (Framemeister is too expensive) and ask for other options anyway.
It's also kind of hard to provide a good stock answer for cheap alternatives because things always seem to be changing on that front. Some hobbyists at shmups will have some solution in the works, but it either takes forever to hit the market or gets shelved indefinitely. HD Retrovision cables are coming but not out yet and are a more limited solution than the PR would have you believe. etc.
NES: RGB mod (<$100 if you can do it yourself; closer to $200 if not), custom AV port (ideally the same as an SNES AV port so that you can share cables between the two systems), and the RGB cable
SNES: just the cable, as long as you have an original model SNES ($20 or so)
Genesis: just the cable ($20)
PS1/PS2: just use the PS2 with official component cables; obtain a component to d-terminal adapter if you need to plug it into an upscaler
Upscaler: either a Framemeister or an XRGB-3; this would run you anywhere from $200 to $300
