If the parents wanted a convincing kidnapping for ransom scenario portrayed, they'd have chosen an appropriate, believeable amount. Remember, in RDI the RN was 'explaining' JBR dead in the basement, so the amount of the ransom wouldn't be lowballed because they wouldn't need to 'part' with any money, as you've claimed. JR and PR working together would come up with an appropriate ransom, and its agreed that 118K was low.
Apart from the fact that genuine kidnappers - certainly strangers or foreigners - would never in a billion years have alit upon that amount. Why not 120k or 100k? 118 may admittedly have had some significance for someone with a grudge against the Ramseys or for someone who didn't really understand the Ramseys' wealth (although if they didn't understand it, then why pick on them and if it's just pure malice, why not just remove JB and never let the Ramseys know whether she is alive or dead?). The Ramseys may have planned complying with their own instructions in order to confound LE and alit upon 118k as an amount they could afford and liquidate easily or because they had no clue how much kidnappers would demand.
Regarding loose ligatures, I can't think that a kidnapper would have much trouble tying a little bairn's hands together behind her back or in front of her. Above her head and falling off all over the place speaks to either someone having no clue or, perhaps to rigor mortis already setting in. If the latter, then discerning the motive of the kidnapper in even bothering to tie the ligatures is nigh-on impossible. If the former, we are coming back to an odd mix of intimate knowledge of the Ramseys and their home and utter lack of planning.
