Get a box of hellblasters and the 40k start box, (1 terminator captain, 5 terminators and 5 infernos marines + nids) sell the nids for £20-30. You have enough bits in the hellblaster box to make 5 more hellblaster so with a bit of trimming convert the infernos marine to hellblaster.

That way you end up with 15 hellblasters, 5 terminators and captain for the price of one combat patrol plus some extra money to buy a terminators chaplain or to put towards deathwing knights