Hi Lacy, a couple of hints if Malaseb is the preferred option:
See whether you can get a repeat prescription from the vet and buy Malaseb
online. Most online prices seem to be about £12.50 and if you can get a prescription for larger quantities or repeat numbers it should save you money long term, even after paying for the prescription. Alternatively explain to the vet you can get it much cheaper online and see if they are willing to provide you with extra discount for bulk purchases.
Apply the Malaseb with a sponge - it makes it go much further
Alternate Malaseb washes with Hibiscrub washes - it should help. A small squeeze of Hibiscrub in half a bucket of water applied with a sponge. There's no need to leave it on but do dry the dog carefully with a towel afterward paying particular attention to creases and folds of skin. The Hibiscrub will keep the areas clean and prevent any secondary infection caused by nibbling and scratching. I haven't used Neem so can't comment but Hibiscrub works exceptionally well for mine. I use
Dermacton too which may be worth a look for your two.