I bought the $4.99 boards from EBAY CHINA back in 2009. They are still working...
The LED lights do not put off RFI by them self. Its the ones that have built-in REGULATOR chips that does the RFI problem... My high dollar LEDs I first purchased wiped out my Ham Radio, WX Radio, and HDTV signals especially when I was using the OTA BATWING antenna.
Read the specs and if the LED works in a range of 11V to 30V or something like that chances are it has a built-in REGULATOR CHIP.
My cheap LED board had the range of 12.0VDC to 14V.0VDC and since my DC Voltage range will go as high as 14.4VDC in my setup I figured I would just order five extra boards in case they started going out me. Since 2009 I only have one LED board that has a three segment LED strip that is out. Still works fine for light... I'm not even sure where my spare boards are now... haha...
This board has the 921 bulb adapter and worked great in my POPUP trailer ceiling lights...
The lesson I learned back in 2009 was to only order one unit and try it out first to see if it what you are looking for before buying a whole compliment of replacement boards...
I have no idea what is hot on the market these days...
Roy Ken