another garage door question

Didnt want to derail the other thread but i have a question for the electronic gurus. I have a garage door opener that is a few years old and pre wifi. I seen online where you can download an app for your droid and make a bluetooth type adapter that attaches to the opener? This would be a good alternative for us vs the standard openers (which i have none of). The 3 of us that use the garage all have smart phones. Anybody done this or familiar with the idea? I dont know where i seen it now but they said you could build the unit cheap with parts from radio shack or buy their $60 unit. Would keep me from having to update a perfectly good opener.