Whatever you call them where you live, they are easy enough to make
Large white floury ones sell for around 65p for 4 in the supermarkets. The cost for 4 large home made is around 30p + cooking. So, as long as you put them in when you are cooking something else, that's half the price.
The recipe I use comes from an issue of The Penny Pincher Paper (more about that HERE) - but with alterations
(Edited in to say I use strong bread flour) I don't use as much yeast,salt,sugar or butter as the recipe, and I use my Kenwood chef with it's dough hook to mix,but do make sure the dough is really soft and when shaping into rolls I try not to handle too much. I don't brush the tops with anything but do sprinkle flour.
I've got a newly concocted recipe for Veggie Burgers which go rather well in these rolls. I'll put that on here sometime soon.