the ILFORD RAPID FIXER 1L TO MAKE 5LT Webcode: 420ILF022 is 11.99, while the 500ml Webcode: 420ILF018 is 7.95 so it is a touch cheaper by the liter. I normaly keep the 1 liter bottle in, and buy a new one for stock once I start to use one. It keeps very well.
BTW, Don't discount freestyle. I order a bunch of stuff from them a couple of times a year. if you shoot enough film the shipping can be worth it.