Have a look at the ingredients. It is mostly Vaseline, not cheap, but supermarkets do their own 'white petroleum jelly' usually in the baby department.
That is as effective as Sudacrem. You pay for the advertising. It may not have the same 'feel' but that is because the Sudacrem is whisked up in the factory. Try it: what have you got to lose? If the white petroleum jelly is not to your taste and feel, there are others cheaper than Sudacrem.
Tesco do an amazing skin cream, which used to be £1 but went up to £1.65. It comes in aloe vera It is amazingly good, comes in the same shape and colour bottle as the vaseline aloe vera equivalent costing £6+. The chiropodist commented on my skin and I said I just get the cheapest