The four-day Ocala Breeders' Sales Co.'s spring sale of 2-year-olds in training ended Thursday with a modest dip in the gross, the average, and the median. The number of horses sold, 774, was the same as were sold at the 2004 auction. The gross of $21.9 million was $1.2 million less than last year. The average of $28,337 and the median of $17,000 were down about 5 percent from a year ago. The buyback rate climbed from 19.9 to 28.6 percent