The ZS1 and ZS3 do not have priority modes.
Which is why I suggested the Canon SX200IS. It has Av, Tv, M, and P modes. Plus it has a 720p movie mode and a 12x (wide-end) zoom. If the manual modes are important, then the SX200IS is the one to get. However, the ZS3 (and TZ5) have better movie modes in that you can use optical zoom while recording.
But then the ZS3 doesn't have the manual modes as you mentioned.
But you can get a used DSLR for that kind of money, hence the FX500, which also starts at 25mm.