You can always use a cheap phone that has ant support - just use it a bike computer exclusively. Some of the older models are getting very cheap now - example my Motorola E was $30 new from Ebay. No need for a mount - just sand the back of the phone and glue on a garmin mount (under $5 on Ebay ) to you favorite garmin mount (eg stem or "out-front" and on ebay for under $5). My whole setup was under $50 and has ant support, maps, the works.