I got my garmin etrex from
www.a1goods.co.uk about 6 months and have had no problems with getting it.
The basic yellow etrex on there is now 79.00. I doubt whether you'll find it cheaper elsewhere.
For anyone else getting one, I'd also get a battery charger, with a couple of rechargeable batteries.
I also download all my journeys from the GPS onto my laptop, so I can see where ive been. The trouble is the memory map navigator software is quite expensive.
Dave