Doenjang and cheonggukjang (Korean fermented soybean products) are reputed to contain B12 and other B vitamins. They might be price-competitive with eggs, and they'd certainly add some welcome taste and variety. Unfortunately, I can't find any source for nutrition information. One would think they would be similar to natto, which has very impressive stats:
However, natto apparently doesn't contain much B12. Natto would be harder to find anyway (and harder to find cheap) since most large cities have Korean grocery stores that cater to budget-conscious customers. If you're looking for cheap, nutritious food, a trip to your local Korean store would be worthwhile for the chance to buy cheap rice and check out the nutrition information on the plastic tubs of doenjang. The cheonggukjang I've bought has not had nutrition information on the label, but it ought to be similar to doenjang or maybe natto.
http://nutritiondata.self.com/facts/legumes-and-legume-produ...
However, natto apparently doesn't contain much B12. Natto would be harder to find anyway (and harder to find cheap) since most large cities have Korean grocery stores that cater to budget-conscious customers. If you're looking for cheap, nutritious food, a trip to your local Korean store would be worthwhile for the chance to buy cheap rice and check out the nutrition information on the plastic tubs of doenjang. The cheonggukjang I've bought has not had nutrition information on the label, but it ought to be similar to doenjang or maybe natto.