I can advise you to get the GPS 60 Csx if available or the GPS 60. easy to use. best unit to use is for the gps unit setup to be in meters.{ http://web.gps.caltech.edu/gislab/Equipment/GPSMAP60CSx_OwnersManual.pdf } find and read it will help you decide.

you can get handheld navigation gps with your budget, moreover you will get accuracy up to several meters. The difference is only the toughness of the gps itself. I think you can get the cheapest one.

 i would recommend an affordable ($300+-) handheld GPS, like Garmin etrex 30x. not to big at hand, and very durable yet simple, in a tropical rainforest (as such the common type of forest in my country). i like my GPS to be a bit water proof (IPX7) enough to withstand a rain or such. as for acc i think it best up to 4-6 m.

i have a GPSmap76Csx & 72H myself (old gps). and it is sure not hand friendly (in my opinion) when im having an outdoor activities like field trip or even hiking, and you got to consider the weight too (also packing size!).. 

but maybe anyone have another opinion.. thanks.

Hi Nicolette,

if you would prefer the low-cost way i suggest use of a BlueTooth receiver connected to the smartphone (tablet). This way you have much more options to choose application and maps, which you'll use. Currently we are testing this one - http://www.gns-gmbh.com/index.php?id=233&L=1

If the accuracy you need is under 10m, perhaps the smartphone alone could suffice. In our recent study we tested several smartphones and achieved mean error of 7.5m under leaf-on conditions (5.5m leaf-off and ~2m open area). Tropical forest could be more adverse, but perhaps it is worth a try.

A more expensive GPS unit does not necesarily give you more accurate results. So start with an old smartphone to see if it meets your needs. First test your GPS accuracy with https://play.google.com/store/apps/details?id=com.chartcross.gpstest&rdid=com.chartcross.gpstest (do this in an open area and then in the forest so you can see how the canopy affects the results. Then maybe use one of the many free GPS logger apps such as https://play.google.com/store/apps/details?id=com.mendhak.gpslogger or https://play.google.com/store/apps/details?id=eu.basicairdata.graziano.gpslogger. Assuming that the location error has a normal distribution, you can take several readings at say 10s intervals and average them. That should give you a fairly accurate location.