How much distance could I be losing with cheap irons?

Thanks for the replies, I guess it's a case of my swing is loosing me some distance but probably so are my clubs. I'll keep my clubs for now & in a few months I'll have to think about upgrading, if I have the money.

In the meantime one day I'll borrow the clubs one of the other lads play with to see how far I can hit them at the driving range compared to my own.