650 looks to be the one to go for. It's got a camera, a bigger memory and a rechargeable battery pack.

http://www.handtec.co.uk/garmin-oregon-650.html

But don't take my word for it as I have merely looked on the inter web.

Edited to add.

On 2nd thoughts, may be not as there appears to be no maps. http://www.ebay.co.uk/itm/GARMIN-TOPO-MAP-ALL-GREAT-BRITAIN-V2-DATA-CARD-for-Astro-eTrex-Colorado-Oregon-/191399067510?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item2c9045ff76

On the Oregon 650 the NiMH Rechargeable Battery 'pack' is in effect two 2.4v 2000mAh batteries with a bit of plastic to hold them together, this bit of plastic presses down a switch in the battery compartment that allows the unit to be used as a charger when plugged into external power, other than that I'm sure that you can get better batteries far cheaper.

EDIT: You may wish to wait for 'Black Friday' to get a good deal online, also last year Garmin themselves issued a 30% discount code purchasing via their own website, maybe they could do this again?

Throw a spanner in the works by suggesting a look a the Runbo range of phones. Going by the specs: dedicated GPSr durability, very long battery life, run android OS so you can use c:geo app and load offline maps, fairly decent cameras, and are also walkie talkies.

http://en.runbo.net/productview.php?id=226

Not cheap, but I am still have an eye on.

Nice looking bit of kit, and spare batteries are available though, £360.00 is a lot to pay for a 2G phone though.
My old Motorola XT890 has gorilla glass, a pretty good battery life and the GPS is good.  There is a newer version out now, that L has, and the battery seems to last ages.  She bought hers with Tesco vouchers rather than go contract

i have done a lot of research on options including testing this forum but have not found any phone/gps hybrids  other than of course the ubiquitous ipads,Androids and mobile apps. which are not a patch on dedicated gps for serious caching.
Maybe,one day? Probably!

Forgot to say I received my  New Garmin 650 yesterday from Handtec via Amazon within 24 hours of ordering it for £282.90 plus £5.95 post and package.
As this is my Christmas present from Mrs S-of-A, I cannot use it until the day but I have negotiated release of the quick start manual (first year level) but online info.much more helpful,but not from Garmin where the "proper" manual is currently unavailable.Don't you just love em?!!

Worth registering it via: http://www.geocaching.com/garmin/freetrial.aspx and getting/extending Premium Membership for 30 days...

(Does seem to be 'playing up' at the moment, but the lackeys are aware of the problem!)

Dragons Den?