I'm tempted to replace the whole garage door opener, which costs around $380 from Mitre 10 for the Merlin, or $700 installed by a garage door company. It has the newer remotes, which still cost $80, but they should last a while.
Are there other garage door systems I could look at that have cheaper remotes? I only need two right now, but will probably want another in a year or so.
If I could find a reliable add on remote thingy I'd probably just do that for now.