Any of the Garmin eTrex series would be great, I only got the more expensive version for the added memory that is has and a few other little things, but its not really needed if you don't plan on saving tons of stuff on it.

 

ihave the garmin rino 120 -110 the 120 goes for about 200 and the 110 150 they are purtty good and they have a twoway radio.

 

I was on a commercial flight to salt lake city and I showed 529 miler per hr, I let everyone else off the plane so I could talk to the pilots. It was a Canada air jet. the pilot sd we hit 520 but said the gps is probably more accurate than their air speed indicator. I was using a garmin legend. I lost satalite several times and had to keep it near the window at all times. My neighbor used his in japan on their new bullet train. I don't think there is any limit to the max speed.

 

I hear you jmcrane. I was on the airplane and mine read just over 600 mph. I also had to keep it near the window. My altitude maxed out at 10,000 if I am not mistaken though. I have an E-Trex that is a couple of years old.