Use the 1dollar sales as an opportunity to get reinforced 4/5 eggs for 2.5-4T.
Except for this particular case, it is always cheaper and better to hatch 4/5 through normal eggs. From my experience, it takes usually between 20 and 25 eggs to succeed. I always spare the eggs and datas until I have enough to hatch them all in a row. You can easily determine the amount of datas needed: number of eggs to try X desired phase X input cost. (an exemple: for a 4/5 Impmon who costs 10datas per input, 20 x 4 x 10 = 800. So you will consume 800 datas in the worst case to try all the 20 eggs.)