Chris, you're not paying as much for the hardware, but rather for the Jepp database.
Without the Jepp database, or without a road database for that matter, GPSs can be had for, oh, 50 pounds or so these days.
Personally I own a 99-euro Garmin eTrex Euro (although it was a bit more expensive when I bought it) interfaced to my laptop on which I'm running OziExplorer. In OziExplorer I use self-scanned aviation maps, or whatever map I come across and then cross-reference with an aviation map, click the route together, load it into the eTrex and off I go. I owned all this stuff well before I got into aviation, so the additional investment was time only.