There aren't that many pressurised GA aircraft - especially ones avail for Private Hire - I'd imagine insurance requirements will be quite significant.
Some GA Presurised A/C I can think of off the top of my head are (from cheapest to most expensive)
P210
Some C337 mixmasters
Some Aerostars
C340
C414
C421
Piper Mojave
Beech Duke
Some Twin Aero Commanders (like 685 Grand Commander)
TBM700
Not alot of point in pres endo until you NEED to. There is alot to be said for some good C210 time etc.