External door thats now an internal door

Hi

Me and the boyf have just bought a house and are doing it up as it was in a right old state. Anyway - it has a porch on the front of it. We would like to put a door in between the porch and the hallway but we are having trouble finding one at a reasonable price.

We have seen some nice internal doors that would be ok for what we want but as it was previously the front door to the house it is larger than standard internal door size (I think it is about 33" wide). We want it for keeping the warmth in really as opposed to a security measure. We put our main front door on but it was over a £100 and we dont want to spend that again.

Does anyone know where we can buy either a cheap front door to put on there or a place where we could find a wider internal door?

Thanks.