たいてい: Generally speaking, In general 質がいいものほど: the better the quality of an item is, 値段も高くなる: the more expensive it is. 若い人ほど: "The younger someone is, マナーを知らない: the more ill-mannered he is," とお年寄りは言います: the elderly say. 自慢する人ほど: The more boastful someone is, 本当は: in reality あまりできません: the less excellent he is. See [5] here http://dic.yahoo.co.jp/dsearch/3/2ss/227770/

ありがとうございます＾＾

Also a Japanese learner so take my help with a grain of salt please :) 程（ほど）illustrates the extent of something. If I were to literally translate your sentences: 1) Generally, to the extent of quality, the price too goes up. (Generally price matches material quality). 2) "To the extent of a young person, you don't know manners," said the elderly [man/woman] (You have about as much manners as a little kid) 3) "To the extent that you would brag about a person, [with him] you really can't" (He's not really someone to brag about")