I have just had a Bryton 21 from Rutland Cycles for £70.
You can compare features here.
I have not had a Garmin so can't compare but this works for me.
Sorry I have not responded to this Liamski I have been on Holiday and not been able to access the forum. I'm not sure what a Garmin etrex 30 is, I have googled it and it looks more like a handheld device, can it be mounted on the bike and does it record all the usual info. average speed, elevation etc. If so can you give me an idea of how much you want for it.