For everyone who chooses belt fed weaponry: Where do you intend to find links for your ammo...?
Surplus dealers. Links and belts are easy to find as are the link or belt filling machines to feed them. I get DM-1 belts for about $6/50rd and 1919 cloth belts about $25/250rd and always keep a few thousand rounds of 308 already on links and/or belts. If I want to feed a weapon off of M13 links instead of DM-1's, they are available for about a few cents each and while they are a little more expensive that M13s, M27s are widely available and I 'm pretty sure they can still be had for less than $.10 each. You just need to know where to look. If you buy surplus ammo in bulk you can often find deals on linked ammo; my dealer recently got about 60k-80k of surplus 7.62 NATO on M13 links and in 200rd ammo cans for about $.20/rd.