Rafi's Spicebox April 8
My friend discovered this place when he moved to York a couple of years ago. They make custom curry packs - literally chopping chilis up and mixing spices in front of you - to make an amazing curry by just adding a few extra ingredients. We ordered a couple from their website a few days ago.
I've tried several - the 'Ma's Paretal' above is amazing and a little bit different from your balti, jalfrezi, etc. You can choose how hot you want the curry to be and P&P is charged per pack. For the cost of the spice pack plus other ingredients you can easily feed 4 people for under a tenner. Highly recommended.