Well, some of our very top restaurants offer tasting menus, and at a few of them, that's all they offer (no a la carte options). For example, at Alinea - which was named the top restaurant in the country by several respected sources including Gourmet magazine - you have a choice between the 12-course tasting menu for $145, and the 26-course tour menu for $225. Avenues offers a 4-, 8-, or 15-course tasting menu for $75, $115, and $145, respectively. You can also find tasting menus at Everest, TRU, Charlie Trotter's, and Schwa, among others.
If you are looking for a lower-priced tasting menu, Sweets and Savories offers one (6-7 courses or so, IIRC) and I think it's $60 on Mondays (their BYO night), $70 the other days of the week.