Aldi do a really nice lean steak mince and its only £2.49 for 400g. I just drain any extra fat off and bulk what im making up with beans, veg, tin toms etc in chilli or spag bol. Will make 2 huge portions plus enough for jackets again for 2. Cant get much cheaper than that!!
It's still not syn free hunnybun as its not extra lean.
To the OP, you could try meat free mince as a substitute as it's usually cheaper than its meaty equivalent. Or use it to bulk out the real thing along with pulses, lentils or veggies to make it go further.