kind of an eat all you can type place
No way in hell I'd put money into that. By weight, yes, buffet, mmm. That's probably something better to experiment with on the side as opposed to it being the main business. An extended salad bar type deal might work. Something like the golden corral in the US. Basically, the buffet alone is like $10 or something like that, and if you get it with an entree it's half that. Don't remember the specifics, but the idea was to have them pay for an entree (steak or whatever), and then have them buy a buffet on top of that for $3 or whatever, which they might use once.
No set menu will keep it fresh...but have you ever done that before? Seems like you'd end up trying to win people over with quality and atmosphere instead of a favorite dish. Maybe not such a great idea over here?