If you'd like to use the AGA output on a flat screen, consider getting one which supports 15 KHz input. Quite a lot of flat panels do so. There are two routes - use one which doubles as a flat screen TV, or check if it will support 15KHz input on its VGA connector. I know that at least one popular Korean brand has got a line of monitors belong to the latter group, and Swedish Amiga dealer
GGS-data carries another such brand.