Synology has a list of User Reported Compatible DVB-T Sticks, most of them ranging from 10 to 100€.

There're even cheaper devices perfectly fit for the job, such as this little gizmo...

I was initially planning this change for much later but my Technomate "TM-5400 CI+ USB Super" died and I had to  look for a replacement, with HD support this time preferably.

Since obviously nobody's attending the tech. support mailbox at Technomate,  I decided to ignore their natural successor, the "TM-5402 HD CI+ Super+" and look somewhere else.