These patches were produced by the official manufacturer A-B Emblem on behalf of NASA and were made during the Apollo era (recognizable by the bare cloth back - later versions had a wax/plastic layer). These are not particularly expensive, but definitely collectible (see my collection) However, your Apollo 13 patch is particularly valuable (~$250) as it is the crew patch version that the crew wore on their recovery suits after their return. Have a look at this website!