Electronics, Lighting, & Gadgets - GPS for Navigation Questions

I ride quite often in places I've never been before, particularly in London. This necessitates me all too often stopping at the roadside and hauling out huge cumbersome cycling maps. I'm thinking that satnav would be better in a lot of ways (though I imagine it would take me down the main roads rather than cycle routes; I'm ok with that). What I'm wondering is, what can I get that will work well for a relatively low price. I've been reviewing some of the threads here, and they all seem to assume knowledge I don't have. For instance, there seem to be lots of Garmin eTrex models out there a lot cheaper than the Legend Cx, (see link), but do they come with maps, or not? How can you tell?

http://cgi.ebay.co.uk/NEW-GARMIN-eTrex-HANDHELD-GPS-Receiver-500-Waypoints_W0QQitemZ180157329245QQihZ008QQcategoryZ4668QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

The one you linked to has no mapping. If you look at the "map" screenshot, it shows trail (GPS plots this) and a couple of user-defined symbols. Other than that it's just a blank screen, no topographic info, no streets, no nothing. Additionally, the seller does not advertise maps for this device. If there were any, they would want to sell them as well, as maps can be quite expensive.

Any mapping GPS will have some kind of built-in base map, but that is usually not detailed enough. And as these devices are used for sailing, kayaking, trekking, biking, driving and whatnot, one map is not the best for all purposes.

If in doubt, ask the seller. If you want to make sure, go to manufacturer's web site and check from there. You'll find Garmin for example has categories like "Basic" vs. "Mapping" when it comes to portable GPS devices.

--J

The Garmin legend CX has a moving map and a nice clear screen that I can read without my reading glasses. Some other etrex models don't have maps on the screen. I use my legend CX in my car, walking but biking is the best. You won't regret getting it.