Limit to selling girls/other stuff at once is 20. So to get rid of 1k girls, you'd have to do it 50 times in a row, assuming all 2*s and NO level 5 manyus/3 or 4* girls. Since you'll likely get quite a number of those in 1k pulls, you'd probably do sell all 2*s about 40 times, and have to manually sell/combine 3/4*s and manyus