What hardware and software would you use for capturing bathymetric elevations (depth) in inland waterbodies (lakes and rivers)?
Your device and software budget is $1,000. The budget is a soft target, to get setup, and doesn't include actual data capture. A 17' open boat with outboard motor and a ruggedized laptop running Windows XP Pro and Arcmap (Arcview license) is at your disposal, if you need them. The data captured should be suitable for building a raster elevation model and bathymetric contours. Depths are not expected to exceed 200m. Desired accuracy should be comparable to or better than a standard consumer handheld GPS (Garmin GPSMap, etc.).
(Actually the budget is a sham. If you've got a good solution for $5k or $50k I'd like to know about it too.)