Hi C172XP!   The 406 ELT market has been somewhat dominated by Artex primarily because they came to market first with a reasonably affordable ELT for General Aviation.  The Artex ME-406 "kit" is about $995 and includes antenna, mounting,
install kit and the required panel mounted control.  The most affordable option is the ACK E-04 406 unit (same package)@ about $650. ACK is playing catch-up.  They promised their unit a few years ago but had problems getting FAA approval.  ACK has been around a long time and are a solid company and their E-04 is available now.  Installation is an 8-10 hour deal! Another company recently entered the market offering an 406 ELT with built in GPS.  The ELT406GPS from "Emerging Lifesaving Technologies" or ELT  @ about $1395 offers the additional benefit of transmitting your GPS position thus
making it faster and easier to locate you.  Frankly, if your a price shopper, the ACK is probably okay for you.  If you like the benefit of GPS positioning ... check out the ELT from "ELT"!  Bob Hart APG-Eastern Avionics