Which budget GPS for iPAQ 3630?

I'm looking for a GPS solution on tight budget for my iPAQ 3630.

What i need is
- a cheap GPS,
- an external power source that won't drain the onboard battery.
I got the freeware - flyWithCE (even though i never had the chance to try
it).

What i want is a ligthweigt and compact kit that's easy to carry and install
in different (mostly rented) gliders.

I think my iPAQ is a bit outdated and won't last forever, so i prefer to
invest in a GPS that will fit with a newer model once i get so far.

Hints, ideas and recommandations are very appreciated - offers will be
considered.

Will 250$ / 200? get me going?

regards,
Niels