I need help with understanding why i pay so mutch for bonds?

A corporate bond usually has a par value of $1000. The price of the corporate bond is the percent fo par you are paying for the bond. So a bond priced at 138 is selling for 138% of par, i.e., $1380, not $138. Be careful you understand that - you will buy something for $1380 which will return $1000 at maturity. That's because the coupon interest on these bonds is significantly higher than you could get in the open market for bonds of this quality and these are really long-term bonds (maturing in 2037).

You need to be craeful about these bonds - these are really high duration bonds which means they are very interest rate sensitive. If interest rates start going up the price of these bonds will drop quick - without actually bothering to calculate, I'll bet if interest rates went up by 1%, these bonds would drop in value by 18% or something. That's a pretty big swing for a not huge move in interest rates. These bonds might be great and I am not saying you shouldn't buy them - they are just a big bet on interest rates combined with a bet on J&J's continued fine credit rating. If you don't understand that, you shouldn't buy them.

Edit: You also paid accrued interest on these bonds which is interest owed to the person who currently owns them that you will collect if you buy the bond.