If your in the USA are you sure you have scart RGB output from your consoles? Pretty sure the N64 needs conversion to RGB scart output. So you are going to need scart RGB cables for all your consoles (not normally sold in the US I would of thought) and a RGB conversion for your N64.
Then you could get a Scart RGB to component conversion box which should be cheaper than scart RGB to hdmi.
I can't help thinking your best option is to buy a nice portable CRT set. In the UK they are practically given away and suspect the US is the same. A small 14-17" set would be ideal I think. Not only that it will have absolute zero input lag and if you have any light gun games they will work on a CRT. It's the best option. Try to get a bedroom set with very light use ideally with a trinitron tube. Don't get a widescreen CRT go for a standard 4:3 aspect tv.
