NOTHING OVER $25: That's the take-home for the big Isabel Lu sample sale headed to 629 E. 30th Street on Friday, April 23 and Saturday, April 24. Short frocks with gathers and ruffles, other go-out spring things. Oh, one more take-home: CASH ONLY: That about says it. Arrive with your paper money. Also, Lucca Couture will be holding a sale at the same time, same space.