Ayse produces a plant growth compound by mixing two types of fertilizer: C and Y. This growth compound must contain at least 5 units of nitrous oxide and 8 units of vitamin mix. Fertilizer C and Y cost $2 and $3 per kg respectively. Fertilizer C contains 1.5 units of nitrous oxide per kg and 3 units of vitamin mix per kg. Fertilizer Y contains 5 units of nitrous oxide per kg and 1 unit of vitamin mix per kg. Determine the minimum cost of Ayse's compound.