costings?
well we pay about 170 per device plus whatever the tarrif is, probably about 20 a month
for the server just get a cheap 1U blade jobby, wont cost much, say 1-2k? (DONT run it off the exchange server!)
BES software is about 3k and that'll get your 1st 20 user licences (theyre $99 per CAL)
or, for my activesync idea...
however much the devices are (decent PDAs are about 200 on contract, more like 100quid to a corporate one)
then you'll need... erm... NOTHING

as long as your exchange server is 2003 SP2 and can see the internet
much cheaper
whats your existing internet setup? and do you have any current GPRS users on a corporate VPN (ie we have our own GPRS APN on Orange, goes straight into our network)