Handheld GPS adaptible to aviation

Hi, I'm a PP-ASEL student. Although the rental planes at my club have
pretty good nav equipment, I'm hoping to supplement them with a
handheld GPS that isn't expensive.

Mostly, I'm of the "your chart isn't going to lie to you" school of
pilotage and frugality. But your chart also doesn't tell you where you
are or what direction you're headed. So, I'd like to use an
inexpensive GPS with very basic mapping capability as a supplement to
VOR navigation for VFR.

Aviation GPS's need periodic map updates. So what I'd ideally like is
rather low-end land/marine unit with a basic map (cities, highways,
shoreline, other topographic features) that has available software to
create my own waypoint database of airports and navaids to supplement
the base map.

Anyone using something like that?

BTW, I am familiar with Brian Wade's excellent database for the
Magellan 315. But that's not a mapping unit. I'm trying to do
something similar but with a low-end mapping GPS.

Thanks