First off, yes trading the safety issues with the non-isolated
power supply, which is better ?

OK, using an AT&T part ATT2406ABI, a 100ohm 15W resistor (caddock) and
4 caps, you get a nice 100mA 5VDC supply, tal
king up about 1" x 1.5".  Heatsinking the resistor is mandatory.  Cost
is about $8.00.  In my case, I needed to put this and the PIC and ISD
all in a single gang outdoor enclosure.  Fits quite nicely.  The unit
is sealed and no-one is going to get zapped.  As a safety measure, you
could put the 110 L1 thru a switch that is enabled with the cover on,
disabled with it off, thus protecting it.  Cost for a small 100mA xfrmr
is around $5, plus bridge re

gulator, caps, etc would put it near $8 range.  BUT, small size is what
I needed.