Try to find an older machine from the 60's or earlier if you plan to make more than a few items. The older machines used metal moving components which don't wear out under normal use. Modern machines are made with plastic parts which will wear out especially if you work with heavier outdoor fabrics and webbing. You don't need all kinds of wild stitch patterns and can get by with a straight stitch machine or one with zigzag capabilities which will allow you to bartack. The old straight stitch Singers like the model 15's, 201, and 66 are easy to find, restore, and parts are available if needed. The Singer 401, 403, 501, and 503's are all metal machines with zigzag which show up often on Craigslist. There are lots of other quality machines from european manufacturers too.... Necchi, Pfaff, Viking Husqvarna, Elna, Bernina, etc. You can search the net and find info on the various models that you spot. Read the reviews before buying.
Backpackinglight.com and hammockforums.net have quite a few posts on machines and gear making. This guys videos and threads are quite useful and worth checking out.
http://www.hammockforums.net/forum/showthread.php?t=19006 Good luck.