Stud & Insulation v Insulated plasterboard

[Grumpy Boy]

I need to insulate the soild walls of my barn conversion. The walls are approx. 500mm thick.

Normal suggestions I have been given are to use insulated plasterboard (e.g. Kingspan), which is about 50-70mm thick + 12mm plasterboard.

I checked the cost of these boards and they are quite expensive.

Would vertical studs with normal insulated board 50-70mm thick (e.g. Kingspan) with normal or foil backed plasterboard on top be suitable as I am sure its cheaper.

Thanks.