If you have a conventional ISP at your home/flat location so you have a routeable Internet IP address and therefore can have “fixed” address, e.g. using DYN DNS then you could probably set up a router-router VPN and not need to use either of the VPN subscription services.
Be interested to hear how you get on, I’ve not used the VPNs on DD-WRT but if you get it going I may well follow suit as I’m interested in using the Remote Rig gear.
Martin