Twenty quid with two spools. Then you buy two and can get a lot of options for line strength and can fill three of them properly and still got a spare body.
Looking at Shakespeare bronze RD. £13 FOR THE 2000 series.
Currently I have three Fladen Power 100 fixed spools. They cost £3.15 each including a box and some 6Ib line
If you are very careful the proper line you install won't end up wrapped around the front drag or behind the spool where the grease will reduce four pound line to a 4ozs breaking strain. It might seem daft but I quite enjoy the cranky little buggers... and they are a very satisfying black and as light as a feather.