28-2007 is for "Christmas", and again they made one poor issue, with stamp full of colors, without clear-cut picture, and hardly that someone will recognize this stamp like something worth to look! Set of 2 value will take from You 2.26 $, and FDC will go for 3.26 $.
29-2007 finally some light on design, and they made it well! Celebrating 50 year of launching SSSR's satellite "Sputnik", Serbian Post made one good design, with visible element, and I think worth to purchase it.
Single stamp will cost You 2.20 $, sheet of 10 identical stamp 22.20 $, FDC 3.80 $ - again, I think that even sheet of 10 will be worth to purchase.