A RAM card probably won't be as useful. The CPU on an unexpanded A1200 won't play many demos and some games, regardless of how much RAM you have. Also, these accelerators are't likely to get cheaper in the future so if you sell it now, replacing it later might not be as easy. The main reason I bought my Blizzard IV was because some of my favorite demos required a 68030 or better, though the extra RAM is nice. A RAM card alone won't help for this.
Why do you need a scan doubler/flicker fixer for it? Really, unless you plan on using interlace screen modes, plain old unmodified Amiga video output is all you need. Get a 1024 monitor off ebay and that'll serve you well. For that matter, since the 1200 has color composite output, you can just hook it up using a standard 3 plug RCA audio/video cable like for a VCR. Hooking it up to any TV should give decent enough video for your needs.
