I've gone a bit overboard on whitening products. What do I keep?

[SlightlySuperiorPeasant]

In an attempt to rescue DH's shirts I started soaking whites overnight in Vanish oxy-white, then washing with a Glo White sachet and a spoonful of soda crystals. My whites are now very white indeed :o but it's costing a fortune. Soda crystals are only 90p for a big packet and we live in a hard water area so they're useful for reducing the amount of detergent needed, so do I drop the Vanish or the Glo White or both? I was thinking about soaking overnight using soda crystals instead.

[owlface]

Are there any pound shops near you? I get tubs of oxy powder there, works great!