THIS PROCEDURE might be written up (in a more coherent fashion!) to replace the "cheap" (DEM2TOPO) part of step #2http://viewer.nationalmap.gov/viewer/Then at the top of the map on the icon bar, pick the rightmost icon for "eneter coordinates by bounding box" (or whatever it's called) if you want to enter in bounding coordinates by hand, or next to rightmost if you want to use cursor to select on map
Dialog comes up with available data
Check elevation (often near bottom), next
Another box comes up with available data -- arcgrid, grdfloat (flt) or img formats (if available).
So far I've found that (as others suggested) NED actually downloads data in 1 degree by 1 degree chunks. In US, you can get 1/3 arcsecond in many places; in Mexico, you may be limited to 1 arcsecond. For 1 degree by 1 degree, 1/3 arcsecond data typically downloads as an ~10812x10812 element matrix; with single p floating points, that 4 bytes per element. That's how you get ~450 MB.
Scripts for converting among file types are at:
http://gisdata.usgs.gov/website/USGS_Raster_Conversion_Scripts.zipIf you look at the scripts, you'll see they just use GDAL_translate. You can get the GDAL distribution compiled for windows, mac, linux, etc. at various places. I just use gdal_translate (copying the command line in the script, making obvious substitutions) with
flt (GridFloat) format files.
Typically, DEM2TOPO is limited to rather small files. I either use a batch file to run gdal_translate to split the flt or tif file into smaller tiles (which are reassembled in GPSMapEdit) or I use gdal_contour to make shp files which I can import into GPSMapEdit. You'll use either the srcwin or projwin switches with GDAL_translate to extract a portion of the original big tif for processing by DEM2TOPO. For example, I typically break a 10812x10812 file into 16 2703x2703 chunks, e.g. with:
(these are the lines in an command-line bat file)C:\"Program Files"\GDAL\gdal_translate -srcwin 0 0 2703 2703 n33w116.tif n33w116_00.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 2703 0 2703 2703 n33w116.tif n33w116_0a.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 5406 0 2703 2703 n33w116.tif n33w116_0b.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 8109 0 2703 2703 n33w116.tif n33w116_0c.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 0 2703 2703 2703 n33w116.tif n33w116_a0.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 2703 2703 2703 2703 n33w116.tif n33w116_aa.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 5406 2703 2703 2703 n33w116.tif n33w116_ab.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 8109 2703 2703 2703 n33w116.tif n33w116_ac.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 0 5406 2703 2703 n33w116.tif n33w116_b0.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 2703 5406 2703 2703 n33w116.tif n33w116_ba.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 5406 5406 2703 2703 n33w116.tif n33w116_bb.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 8109 5406 2703 2703 n33w116.tif n33w116_bc.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 0 8109 2703 2703 n33w116.tif n33w116_c0.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 2703 8109 2703 2703 n33w116.tif n33w116_ca.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 5406 8109 2703 2703 n33w116.tif n33w116_cb.tif
C:\"Program Files"\GDAL\gdal_translate -srcwin 8109 8109 2703 2703 n33w116.tif n33w116_cc.tif