Natasha
Don't be fooled into thinking that commercial products are the be-all and end all, because you'll find a lot of sucessful cleaning companies still buy from supermarkets and pound shops.
For bathroom cleaning, a good washing up liquid is what is mostly needed (Asda do two 500ml bottles for £1) if the bathrooms are averagely dirty. If you want a spray, buy a multipurpose cleaner like Cif or Flash and dilute 2 caps to 500ml water in a sprayer.
Also, dont always go for the brand-names, experience will tell you which branded products and which cheap /supermarket-named products give best results. Some of the cheap products are superb.