LowNSlow,
Garmin website is at:-
http://www.garmin.com/aviation/index.html
Magellan website is at:-
http://www.magellangps.com/
(look under consumer products, then under aviation)
My Skyblazer XL also hungry on batteries (most older GPS rx are) but has a dc power input which I use as a matter of routine.
Magellan website also has product support details for older models, might be useful.
Haven't found the Lowrance homepage but I got info on their aviation GPS via a search engine looking at pilot's supplies websites.
If my Skyblazer croaked, I'd get either a Garmin Pilot III or the more expensive Pilot 295 with colour LCD display. Have seen both, very nice! The Magellan Sky Star Plus International is also very nice but the yoke-clamp is plastic and prone to breakage, not sure how easy to get replacements. I also prefer the layout of control buttons on the Garmin.
Suggest get prices from online pilot's suppliers, then check out what your local blokes can do. Shopping around might prove useful.
Hope this helps.