I need to transmit digital data, from an Arduino, Raspberry or alike, but using VHF band (aprox 150 MHz), would anyone care to suggest a cost effective device to use as transceiver? 10W would be desired, but 5W will also be accepted.
I once spent a bit of time getting packet radio going over VHF using a Raspberry Pi and Direwolf as the modem. It worked fine using a couple of cheap Wouxon handhelds. (I've heard that Baofengs don't work as well due to the time it takes to break the squelch.)
The instructions I used are here: https://andrewmemory.wordpress.com/2016/03/31/turning-a-raspberry-pi-2-into-a-packet-station/. In short, set the Pi up as a packet node, then use Direwolf and kissattach to provide TCP/IP over packet into a sound card. Too much for an Arduino, but should be fine on a Pi.
They required a Signalink to do the PTT, but I think Direwolf can do the PTT itself with an appropriate cable.
I'll leave the legalities of it up to you - but packet radio is designed for multiple stations, can route traffic through nodes (and in fact is TCP/IP), and appropriate Wouxuns can transmit 1200 baud packet at 147 MHz, so should be able to handle it at 150 MHz.