This is a listing of all Minolta AF cameras with specs:
http://web.archive.org/web/20060413211332/http://www.photozone.de/2Equipment/minoltacamera.htm
You can see, that the 7 and 9 are the best equipped camera, f.e. mirror lock-up only with these two models. The 5 that you already have is imho the best of the small and light models. So 5 and 7 would be my choice. If you do a lot of vertical/portrait orientated pics, the 600si, 700si or 800si with accessory battery grip have a vertical format shutter button and additional setting wheels and buttons, that is simply unbeatable ergonomics. The same goes of course for the 7 with battery grip. A 700si with battery grip goes for less than 100 bucks, a 7 without for (much?) more than 100.
To buy a camera is no problem, but lenses are. Fast lenses are rare and expensive, prime lenses are rare and expensive, the 1.7/50 AF for 100 bucks is nice but not a killer. Zoom lenses without wide-angle distortion are more or less not available, a problem with all affordable zooms. Stay away from all XI-lenses, their motor driven zoom is the worst thing on earth. Look for older and fast Sigma lenses, they are not so expensive because many of these have problems with the digital Alphas, many are not compatible, so they have bad reputation for the use with digital cams.
I have a 5, a 700si with battery grip and a Alpha100, all are nice, but the dark (all AF-slr) and small (A100) screens are nothing compared with a big bright MF screen and fast prime lenses, and all the latter you get dirt cheap.