Use promo code BONUS97OFF and your first year should come out at 22.40 (or about 1.87 a month-- but you can't pay monthly =] )
You can also use the same code on a 2 year plan, to take $97.00 off.
Note that promos are only valid for your first 1 or 2 years.
Dreamhost's "sales" are never 'announced' but anytime there is a US holiday you can almost count on there being one. My best guess is the next one is Labor Day Weekend.