Low cost options - Product features.

 These products allow wireless silent TV, iPod, phone and game listening.  Also for the hearing impaired. Transmit stereo from your portable music player to your car or home FM radio. For car use only, the non-battery types powered by cigarette lighter may be all you need. For a few dollars more you can get all the bells and whistles - if you shop around.

Features to consider:

• Frequency range. The best offer a full range 87.5-108.0 MHz in 0.1 MHz increments. Smaller ranges like 88.1-88.7 may work fine - since the transmitter "typically" overpowers outside signals. 
• Channel memory. Gives you several transmit options - for different locations (house, car, city, etc) or for different devices. Makes it easier to return to your preferred station without retuning. 
• ON/Off.  Consider ? auto shutoff if you don't have rechargeable batteries (consider getting some for your remotes, mouse, etc.) 
• Power Adapters. Most cigarette lighter transmitter adapters will only power the transmitter, not charge the batteries or service other devices. If the adapter is designed to power both - make sure (email the seller) it will work with your specific device.

Model Notes

200 CHANNEL FM TRANSMITTER. Model 668A. Similar to Belkin Tunecast II, without auto poweroff.  

• 3 channel memories, 24hour clock, Celsius Thermometer  
• Backlit display activates for 3 sec during selections 
• "Transmit distance >5m" Good reception similar to my cordless phone. 
• Includes lighter power adapter with USB to (mini?)USB cord.
  

Dynex Wireless FM Transmitter 

• Channel switch: 88.1 88.3 88.5 88.7, with fine-tune thumbwheel 
• On/Off button with indicator light 
• Battery only 
• Distance: within a room, at best. Poor sound quality (may have been my unit - an open box item)